CPAP systems · AirLife family

Cardinal Health AirLife nCPAP: troubleshooting and error codes

The ServiceForge knowledge base holds 71 documented symptoms for the Cardinal Health AirLife nCPAP, with 90 ranked causes, 81 diagnostic checks with test points and expected values, and 24 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Power-on self-test: Insufficient or missing gas source pressure

Air and/or oxygen gas sources not connected or below minimum 41 psig

Ranked causes

1. Gas source not connected or below minimum pressure (common)
2. Clogged inlet filter screens (occasional)
3. Faulty or defective inlet pressure sensor (rare)

First check

Verify gas sources are connected

Test point: air and oxygen inlet connectors
Expected: both sources connected securely

2 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Battery not charging

Battery icon does not show lightning bolt indicating charging status after AC Adapter connected

Ranked causes

1. AC Adapter not connected or loose connection (common)
2. Defective battery or charging circuit (rare)

First check

Verify AC Adapter is properly connected

Test point: Power connector on back of driver
Expected: AC Adapter fully seated; lightning bolt visible in battery icon

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Bleed flow outside specification caution

Measured bleed flow rate not within acceptable range with circuit and generator connected

Ranked causes

1. Loose internal plumbing connections (common)
2. Kinked tubing restricting flow (occasional)

First check

Measure bleed flow rate

Test point: Bleed flow outlet port on bottom housing
Expected: 0.7 to 3.0 LPM (acceptable range at inlet pressure 41-66 PSI), 0.7-3.0 LPM
Tools: Flow meter

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

FiO2 delivery outside tolerance patient safety

Oxygen concentration delivered does not meet ±3% accuracy specification at set points

Ranked causes

1. Incomplete warm-up calibration (occasional)
2. Independent O2 sensor not calibrated (occasional)

First check

Measure FiO2 at 21% setpoint

Test point: Driver LCD screen and patient outlet via independent analyzer
Expected: Within ±3% of setpoint (18-24%), ±3%
Tools: O2 analyzer, DMM

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Gas source pressure out of range patient safety

Driver alarms and displays source fault when one gas source falls outside 41-66 psig range

Ranked causes

1. Medical air or oxygen supply pressure outside specified range (41-66 psig) (occasional)
2. Gas supply line not connected or switched to new source (common)

First check

Verify gas source pressures

Test point: Medical air and oxygen supply regulators
Expected: Both sources regulated at 41-66 psig (nominal 50 psig)

1 more check with pass and fail actions, 4 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low battery power remaining caution

Audible and visual alarm with dual thresholds; Medium Priority at <10% (approx. 24 minutes remaining); High Priority at <5% (approx. 12 minutes); 2-second delay

Ranked causes

1. Battery charge depletes below 10% capacity (common)
2. Battery charge depletes below 5% capacity (common)

First check

Monitor battery capacity display

Test point: Battery indicator on screen
Expected: Above 10% capacity

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low flow alarm activates patient safety

Low Flow alarm activates during operation, measured flow rate less than 3 lpm

Ranked causes

1. Occluded expiratory limb or kinked tubing (common)
2. Defective patient circuit or generator (occasional)

First check

Measure flow rate at patient circuit connection

Test point: Patient Circuit Connection
Expected: Greater than or equal to 3 lpm

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low pressure in patient circuit patient safety

Pressure 2 cm H2O below set value; audible alarm, yellow flashing warning LED, message bar

Ranked causes

1. Leak in tubes, circuit, nasal prongs or mask (common)
2. Insufficient supply gases (common)

First check

Inspect circuit for leaks or disconnections

Test point: tubes, circuit, nasal prongs, mask connections
Expected: all connections sealed, no visible leaks

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Patient treatment mode: Air pressure below minimum during operation patient safety

Air source pressure dropped below 41 psig; user may remove device from service or select Oxygen Only mode (FiO2 goes to 100%)

Ranked causes

1. Air source pressure below minimum 41 psig (common)
2. Faulty inlet pressure sensor (rare)

First check

Verify air supply pressure is at least 41 psig

Test point: air inlet pressure gauge or regulator
Expected: minimum 41 psig

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Patient treatment mode: Air pressure exceeds maximum during operation patient safety

Air source pressure exceeded 66 psig; user may remove device from service or select Oxygen Only mode (FiO2 goes to 100%)

Ranked causes

1. Air source pressure above maximum 66 psig (common)
2. Faulty inlet pressure sensor (rare)

First check

Verify air supply pressure does not exceed 66 psig

Test point: air inlet pressure gauge or regulator
Expected: maximum 66 psig

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Patient treatment mode: Air source disconnected or depleted patient safety

Air source has become disconnected, tank run out, or hose/fittings leaking excessively; FiO2 drops below specification

Ranked causes

1. Air source disconnected, tank empty, or excessive leak (common)
2. Clogged inlet filter screen (occasional)

First check

Verify air tank is connected and contains gas

Test point: air tank connection and regulator
Expected: connected securely, tank not empty

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Patient treatment mode: Oxygen pressure below minimum during operation patient safety

Oxygen source pressure dropped below 41 psig; user may remove device from service or select Air Only mode (FiO2 goes to 21%)

Ranked causes

1. Oxygen source pressure below minimum 41 psig (common)
2. Faulty inlet pressure sensor (rare)

First check

Verify oxygen supply pressure is at least 41 psig

Test point: oxygen inlet pressure gauge or regulator
Expected: minimum 41 psig

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Patient treatment mode: Oxygen pressure exceeds maximum during operation patient safety

Oxygen source pressure exceeded 66 psig; user may remove device from service or select Air Only mode (FiO2 goes to 21%)

Ranked causes

1. Oxygen source pressure above maximum 66 psig (common)
2. Faulty inlet pressure sensor (rare)

First check

Verify oxygen supply pressure does not exceed 66 psig

Test point: oxygen inlet pressure gauge or regulator
Expected: maximum 66 psig

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Patient treatment mode: Oxygen source disconnected or depleted patient safety

Oxygen source has become disconnected, tank run out, or hose/fittings leaking excessively; FiO2 drops below specification

Ranked causes

1. Oxygen source disconnected, tank empty, or excessive leak (common)
2. Clogged inlet filter screen (occasional)

First check

Verify oxygen tank is connected and contains gas

Test point: oxygen tank connection and regulator
Expected: connected securely, tank not empty

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Power-on self-test: Excessive gas source pressure

Air and/or oxygen gas sources exceed maximum 66 psig

Ranked causes

1. Gas source pressure above maximum specification (common)
2. Faulty or defective inlet pressure sensor (rare)

First check

Measure gas source inlet pressures

Test point: air and oxygen inlet pressure
Expected: 41–66 psig (maximum 66 psig)

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Power-on self-test: Insufficient oxygen sensor bleed flow

Oxygen sensor bleed flow below 0.9 lpm at 50 psig; 2-point O2 sensor calibration criteria not met

Ranked causes

1. Occluded oxygen sensor bleed port or inlet filter screens (common)
2. Faulty or defective O2 sensor (rare)

First check

Inspect and clean inlet filter screens and O2 sensor filters

Test point: inlet filters and oxygen sensor area
Expected: clean, unobstructed

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Power-on self-test: Patient circuit pressure not cleared patient safety

Pressure elevated in patient circuit during start-up; patient pressure sensor failed zero calibration

Ranked causes

1. Proximal pressure line connected or pressure trapped during startup (common)
2. Faulty or defective patient pressure sensor (occasional)

First check

Disconnect proximal pressure line and cycle power

Test point: proximal pressure line connection to device
Expected: disconnected, then device powered off and on

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Unit does not power on or LEDs do not illuminate

After powering on unit, LEDs fail to illuminate during power-on self test

Ranked causes

1. AC Adapter not properly connected or defective (common)
2. Incorrect AC Adapter type (occasional)

First check

Verify AC Adapter is connected to driver power connector

Test point: Power connector on back of driver
Expected: AC Adapter fully seated and connected to properly grounded AC outlet

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Air filter dirty or wet

Inlet air filter and water trap on back of driver appear soiled or contain moisture

Ranked causes

1. Normal accumulation of dirt or moisture in air filter (common)

First check

Visually inspect inlet air filter and water trap

Test point: Back of driver
Expected: Filter clean and dry

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Air pressure high patient safety

Audible alarm, red flashing fault LED, message bar

Ranked causes

1. Air supply pressure exceeds specification (common)

First check

Verify air supply pressure does not exceed maximum

Test point: air inlet pressure gauge or regulator
Expected: 41–66 psig (maximum 66 psig)

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Air pressure low patient safety

Audible alarm, red flashing fault LED, message bar

Ranked causes

1. Air supply pressure below specification (common)

First check

Verify air supply pressure is within specification

Test point: air inlet pressure gauge or regulator
Expected: 41–66 psig

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Alarm mute and system startup delay patient safety

Alarms delayed 120 seconds after entering Patient Treatment Mode for patient setup; can be muted an additional 120 seconds by pressing Alarm Mute/Reset button or entering Standby Mode

Ranked causes

1. User needs additional time for patient setup beyond initial 120-second delay (common)

First check

Observe alarm behavior after Patient Treatment Mode entry

Test point: System timer and alarm status
Expected: Alarms inactive for 120 seconds; Alarm Mute/Reset button responsive

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Battery charge fail caution

Audible and visual alarm indicating battery is not charging properly; verified at startup and during operation; 5-second delay

Ranked causes

1. Battery fails to charge during normal charging operation (rare)

First check

Observe battery charge indicator

Test point: Battery level display during charging
Expected: Battery capacity increasing while connected to charger

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Battery charge fault

Audible alarm, red flashing fault LED, message bar, red power LED, LCD indicator active

Ranked causes

1. Battery charging circuit malfunction or defective battery (common)

First check

Verify AC adaptor is always connected during operation

Test point: AC adaptor connection
Expected: connected to power at all times

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Battery charging not indicated

Lightning bolt icon, green LED, plug icon, or 'Charge' text not illuminated/displayed during AC power connection

Ranked causes

1. Charging system malfunction (unknown)

First check

Observe charging indicators with AC power connected

Test point: Battery icon, LED at plug decal, LCD display
Expected: Lightning bolt icon illuminated, green LED lit, plug icon displayed, 'Charge' text shown

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Battery insufficient run time

Battery operates less than 4 hours on full charge, or low battery alarms do not activate

Ranked causes

1. Battery aged beyond 2 year service life (common)

First check

Monitor battery run time and alarm activation

Test point: Battery icon and audible alarms
Expected: 4 hours total operation including low battery alarm periods; low battery alarms activate before shutdown

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Battery low (critical level)

Approximately 12 minutes remaining; audible alarm, red flashing fault LED, message bar, red power LED

Ranked causes

1. Battery critically depleted on DC power (common)

First check

Verify AC adaptor is connected

Test point: AC adaptor connection to device
Expected: connected to power source and device

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Battery low (medium level)

Approximately 24 minutes remaining; audible alarm, yellow flashing warning LED, yellow power LED

Ranked causes

1. Battery discharging on DC power without AC charging (common)

First check

Verify AC adaptor is connected to charger port

Test point: AC adaptor connection
Expected: connected and charging initiated

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Bleed flow not dropping to zero

Bleed flow continues when main power switch is turned off

Ranked causes

1. Valve malfunction or stuck solenoid (unknown)

First check

Verify bleed flow stops on power-off

Test point: Bleed flow outlet port
Expected: Zero flow when power switch off

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Circuit disconnect detected patient safety

Audible alarm, yellow flashing warning LED, message bar; flow rate adjusted to target ±2 lpm

Ranked causes

1. Leak or disconnection in circuit, nasal prongs or mask (common)

First check

Inspect circuit for leaks or disconnections

Test point: all tubing and interface connections
Expected: all connections sealed and secure

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

CPAP pressure outside tolerance patient safety

Delivered CPAP pressure does not meet ±1 cm H2O accuracy at set levels

Ranked causes

1. Prongs occluded or connections not secure (common)

First check

Measure CPAP pressure at 5 cm H2O

Test point: Driver LED bar graph, LCD display, and independent manometer
Expected: 5 ± 1 cm H2O (4-6 cm H2O), ±1 cm H2O
Tools: Manometer

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Elevated CPAP pressure patient safety

Audible and visual Medium Priority alarm; indicates pressure is above target set level

Ranked causes

1. Measured CPAP pressure is 2 cm H2O above set level with 5-second duration (unknown)

First check

Measure CPAP pressure

Test point: Pressure sensor
Expected: Within 2 cm H2O of Set CPAP level, ±2 cm H2O

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Elevated pressure in patient circuit patient safety

Pressure 2 cm H2O above set value; audible alarm, yellow flashing warning LED, message bar displayed

Ranked causes

1. Exhaust tube occluded or restricted (common)

First check

Inspect exhaust tube for occlusions or restrictions

Test point: exhaust tube
Expected: clear, unobstructed flow

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Excessive circuit leak detected patient safety

Leak 3 lpm over target flow rate or flow rate >15 lpm; audible alarm, yellow flashing warning LED, message bar

Ranked causes

1. Leak or disconnection in circuit, nasal prongs or mask (common)

First check

Inspect circuit and interface for leaks

Test point: all connections and patient interface
Expected: no visible leaks, secure connections

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Excessive flow leak detected patient safety

Audible and visual Medium Priority alarm; flow exceeds target by 3 lpm or exceeds 15 lpm; 5-second delay

Ranked causes

1. Flow rate exceeds Target Flow by 3 lpm or absolute flow exceeds 15 lpm for 5 seconds (occasional)

First check

Measure delivered flow rate

Test point: Flow sensor
Expected: Not exceed Target Flow + 3 lpm and not exceed 15 lpm absolute

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Excessive patient leak during CPAP delivery patient safety

Large leak exists at patient interface that cannot be corrected by adjusting mask or prongs; inadequate CPAP pressure maintenance

Ranked causes

1. Improper patient interface fit or positioning (common)

First check

Verify adequate CPAP pressure at patient

Test point: Pressure line connection at patient circuit
Expected: CPAP pressure matches Set value on main screen

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

External power disconnected

Single audible burst, indicator on display, green power LED turns off

Ranked causes

1. AC adaptor unplugged or disconnected (common)

First check

Verify AC adaptor is plugged in

Test point: AC adaptor connector
Expected: connected to power outlet and device

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Fatal software fault patient safety

Continuous audible alarm, red fault LED, warning screen; driver ceases operation, no patient flow

Ranked causes

1. Critical software fault that prevents safe operation (rare)

First check

Immediately disconnect patient from device

Test point: patient interface
Expected: patient safely disconnected

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

FiO2 limit exceeded patient safety

Audible alarm, yellow flashing warning LED, message bar displays 'FiO2 Limit'

Ranked causes

1. Supply gases insufficient or out of specification (common)

First check

Verify air and oxygen supply presence and pressure

Test point: gas inlet connections
Expected: within 41–66 psig range

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

FiO2 warning patient safety

Audible alarm, red flashing fault LED, message bar says 'FiO2 Warning'; device continues CPAP and FiO2 delivery

Ranked causes

1. Supply gases insufficient or sensor drift out of range (common)

First check

Verify gas supplies connected and in specification

Test point: air and oxygen inlet
Expected: 41–66 psig

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Flow or pressure sensor calibration failure patient safety

Audible and visual Sensor Calibration alarm; occurs during Power-On Self Test; device must be removed from service

Ranked causes

1. Flow sensor or pressure sensor fails calibration test during startup (rare)

First check

Complete Power-On Self Test

Test point: Startup sensor calibration sequence
Expected: Both flow and pressure sensors calibrate successfully

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Flow rate outside tolerance patient safety

Delivered flow rate does not meet ±2 LPM accuracy compared to independent flow meter

Ranked causes

1. Circuit or generator connection loose (common)

First check

Measure flow rate at CPAP 5 cm H2O

Test point: Driver LCD display and independent flow meter
Expected: Within ±2 LPM of independent meter reading, ±2 LPM
Tools: Flow meter

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Flow/pressure sensor failure

Audible alarm, yellow flashing warning LED, Sensor Calibration Failure warning screen

Ranked causes

1. Flow or pressure sensor failed zero calibration (common)

First check

Disconnect patient from entire circuit

Test point: patient interface connection
Expected: completely disconnected

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Fuse blown caution

3.0 Amp 250 V fuse on rear of unit has failed

Ranked causes

1. Electrical overload or component failure (unknown)

First check

Verify fuse is blown

Test point: Fuse on rear of unit
Expected: Fuse element intact

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

High pressure alarm not activating patient safety

No audible alarm or visual indication when exhaust port is occluded

Ranked causes

1. High pressure sensor or alarm circuit malfunction (rare)

First check

Occlude exhaust port and observe alarm

Test point: Audible alarm and LCD display
Expected: High pressure alarm activates immediately with CPAP and flow dropping to zero

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

High pressure in patient circuit patient safety

Audible and visual High Priority alarm; pressure relief solenoid activates and patient delivery solenoid closes, reducing circuit pressure to zero; system reinitializes flow every 3 seconds

Ranked causes

1. Patient circuit pressure exceeds 12 cm H2O for 2 seconds or reaches 18 cm H2O (unknown)

First check

Monitor circuit pressure during operation

Test point: Pressure sensor reading
Expected: Below 12 cm H2O, Normal operating range

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low air inlet pressure alarm not activating patient safety

Audible alarm and 'Air Pressure Low' message do not appear when air source is disconnected

Ranked causes

1. Air inlet pressure sensor malfunction (rare)

First check

Observe alarm on air source disconnect

Test point: Audible alarm and LCD message bar
Expected: 'Air Pressure Low' message with high priority red flashing LED and audible alarm

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low CPAP pressure patient safety

Audible and visual Medium Priority alarm; indicates pressure is below target set level with 14-second delay

Ranked causes

1. Measured CPAP pressure is 2 cm H2O below set level for 14 seconds (unknown)

First check

Measure CPAP pressure

Test point: Pressure sensor
Expected: Within 2 cm H2O of Set CPAP level, ±2 cm H2O

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low flow delivery patient safety

Audible and visual High Priority alarm; flow rate at or below 3 lpm; 10-second delay

Ranked causes

1. Delivered flow is ≤3 lpm for 10 seconds (common)

First check

Measure gas supply inlet pressures

Test point: Supply pressure inlet
Expected: Within specified gas supply range

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low flow detected patient safety

Flow rate ≤3 lpm; audible alarm, red flashing fault LED, message bar

Ranked causes

1. Exhaust tube occluded or restricted (common)

First check

Inspect exhaust tube for blockages

Test point: exhaust tube
Expected: clear, unobstructed

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low oxygen inlet pressure alarm not activating patient safety

Audible alarm and 'Oxygen Pressure Low' message do not appear when oxygen source is disconnected

Ranked causes

1. Oxygen inlet pressure sensor malfunction (rare)

First check

Observe alarm on oxygen source disconnect

Test point: Audible alarm and LCD message bar
Expected: 'Oxygen Pressure Low' message with high priority red flashing LED and audible alarm

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low pressure/disconnect alarm not activating patient safety

No audible alarm or visual indication when prongs are removed or circuit disconnected

Ranked causes

1. Pressure sensor or alarm circuit malfunction (rare)

First check

Remove prong occlusion and observe alarm response

Test point: Audible alarm and LCD message bar
Expected: Medium priority audible alarm with yellow LED and 'Disconnect' or 'Low Pressure' text within 15 seconds

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Mechanical high pressure relief not within specification patient safety

Pop-off pressure measured at patient outlet not within 211 ± 22 cm H2O

Ranked causes

1. High pressure relief valve setting out of adjustment (unknown)

First check

Measure dead-head pressure at patient outlet

Test point: Patient outlet port with high range manometer
Expected: 211 ± 22 cm H2O (189-233 cm H2O), ±22 cm H2O
Tools: High range manometer (≥250 cm H2O capability)

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Non-fatal software fault

Audible alarm, red flashing fault LED, message bar

Ranked causes

1. Software fault detected by watchdog that does not affect operation (unknown)

First check

Note and record the displayed fault code

Test point: message bar or LCD display
Expected: specific fault code visible

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Oxygen Bleed Flow out of specification

Oxygen Bleed Flow measured at the Oxygen Sensor Bleed Port does not fall within acceptable range, indicating potential FiO2 accuracy issues

Ranked causes

1. Loose connections or kinked tubing in driver plumbing (common)

First check

Measure Oxygen Bleed Flow at Oxygen Sensor Bleed Port on underside left-rear of driver

Test point: Oxygen Sensor Bleed Port
Expected: 0.9 to 3.0 lpm at 50 ± 1 psig inlet pressure; acceptable range 0.7 – 3.0 lpm at 41 – 66 psig, 0.7 – 3.0 lpm
Tools: Flow meter

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Oxygen concentration out of range patient safety

Audible Medium or High Priority alarm; FiO2 outside ±3% tolerance with variance-duration product exceeding threshold

Ranked causes

1. Variance from set FiO2 exceeds ±3% for duration where variance×seconds >20 (Medium) or >30 (High) (occasional)

First check

Measure actual FiO2 output

Test point: Oxygen sensor
Expected: Set %O2 ±3%, ±3%

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Oxygen pressure high patient safety

Audible alarm, red flashing fault LED, message bar

Ranked causes

1. Oxygen supply pressure exceeds specification (common)

First check

Verify oxygen supply pressure does not exceed maximum

Test point: oxygen inlet pressure gauge or regulator
Expected: 41–66 psig (maximum 66 psig)

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Oxygen pressure low patient safety

Audible alarm, red flashing fault LED, message bar

Ranked causes

1. Oxygen supply pressure below specification (common)

First check

Verify oxygen supply pressure is within specification

Test point: oxygen inlet pressure gauge or regulator
Expected: 41–66 psig

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Oxygen sensor calibration error patient safety

Audible alarm, red flashing fault LED, Oxygen Calibration Error warning screen; device provides CPAP and FiO2 but FiO2 may not be accurate

Ranked causes

1. Oxygen sensor malfunction or calibration criteria not met (common)

First check

Remove patient and power cycle device

Test point: power button
Expected: device powers off then restarts

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Patient circuit disconnect or loose connection patient safety

Audible and visual Medium Priority alarm; detects pressure line or patient interface disconnect; 5-second delay

Ranked causes

1. Flow and pressure conditions meet alarm thresholds simultaneously (e.g., flow ≥6 lpm AND CPAP ≤2 cm H2O for 5 seconds) (common)

First check

Verify patient interface connection

Test point: Patient interface attachment point
Expected: Securely seated with no visible gaps

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

More symptoms

Patient treatment mode warning: Non-fatal software fault detected
Patient treatment mode warning: Oxygen sensor drift calibration failure
Patient treatment mode warning: Running on DC power beyond 4 hours
Patient treatment mode: High FiO2 warning for prolonged delivery
Power loss not indicated
Power-on self-test: Flow sensor failure
Power-on self-test: Oxygen sensor calibration failure
Power-on self-test: Source valve or delivery valve failure
Software fault detected
Standby Mode operation
Supply gas pressure out of range

11 more symptoms with ranked causes and checks are in ServiceForge. Connect ServiceForge to your AI

Error codes

Code	Meaning	Trigger	Severity
`Air Pressure High`	Air inlet pressure exceeded maximum 66 psig	Supply pressure rises above specification during operation	critical
`Air Pressure Low`	Air inlet pressure dropped below minimum 41 psig	Supply pressure falls out of specification during operation	critical
`Alarm Mute/Reset button function`	Resets alarm state after High Priority condition clears; provides additional 120-second mute window during patient setup	User presses Alarm Mute/Reset button after High Priority alarm or during patient setup initialization	info
`Battery Charge Fault`	Battery charging circuit has failed; device cannot charge battery	Detected during power-on self-test or during operation	critical
`Battery Low Dual Stage Alarm (~12 minutes remaining)`	Battery charge level critically depleted with minimal time before shutdown	Continued battery operation without AC input after initial warning	critical
`Battery Low Dual Stage Alarm (~24 minutes remaining)`	Battery charge level critically low with medium remaining time	Device operating on battery power for extended period without AC input	warning
`Disconnect (Table Based)`	Circuit disconnect detected by pressure or flow monitoring	Tubing or interface disconnection develops during operation	warning
`Elevated Pressure (2 cm H2O over Set Value)`	Pressure in patient circuit 2 cm H2O above the set pressure	Exhaust tube occlusion or restriction develops during operation	warning
`External Power Disconnect`	AC adaptor has been unplugged; device switched to battery	AC adaptor cable removed from power outlet or device connector	info
`Fatal Software Fault`	Critical software error; device ceases operation immediately	Software failure detected by watchdog that prevents safe operation	critical
`FiO2 Limit`	Oxygen concentration cannot be maintained within specified range	Oxygen supply fails or becomes insufficient during operation	warning
`FiO2 Warning`	Oxygen concentration drifted outside specification; alarm active but therapy continues	Oxygen sensor calibration criteria not met; oxygen supply degradation	critical
`Flow/Pressure Sensor Failure`	Flow or pressure sensor failed zero-point calibration during startup	Detected during power-on self-test; prevents normal operation	info
`High Pressure`	Pressure in patient circuit exceeds safe limits	Patient circuit pressure rises above safe operating threshold during therapy	error
`High Pressure (≥12 cm H2O for 2 seconds or ≥18 cm H2O instan`	Pressure in patient circuit critically elevated; safety release activated	Exhaust obstruction or system malfunction during patient therapy	critical
`High Priority alarm (flashing Red Fault LED)`	High priority alarm condition detected; audible alarm active; Red Fault LED flashes	High priority alarm condition occurs (e.g., High Pressure, Low Flow, Software Fault, Oxygen Calibration, Source Pressure)	critical
`Leak`	Excessive leak detected in patient circuit (>3 lpm above target)	Large leak or disconnection during patient therapy	warning
`Low Flow`	Measured flow rate is less than 3 lpm	Flow rate detected at patient circuit drops below 3 lpm during operation	warning
`Low Pressure (2 cm H2O under Set Value)`	Pressure in patient circuit 2 cm H2O below the set pressure	Leak in circuit or supply gas insufficient	warning
`Medium Priority alarm (Yellow Warning LED)`	Medium priority alarm condition detected; audible alarm and Yellow Warning LED active	Medium priority alarm condition occurs (e.g., Elevated Pressure, Low Pressure, Disconnect, Leak, Low Battery)	warning
`Non-Fatal Software Fault`	Software error detected by watchdog that does not prevent operation	Software anomaly detected during self-test or operation	error
`Oxygen Pressure High`	Oxygen inlet pressure exceeded maximum 66 psig	Supply pressure rises above specification	critical
`Oxygen Pressure Low`	Oxygen inlet pressure dropped below minimum 41 psig	Supply pressure falls out of specification during operation	critical
`Oxygen Sensor Calibration Error`	Oxygen sensor failed 2-point calibration; device cannot verify FiO2 accuracy	Oxygen sensor malfunction detected during calibration or periodic check	critical

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ServiceForge knowledge base record. Field-unverified unless technicians confirmed it. A teaching summary of the record, not a service manual. Export 2026-10-14.