Anesthesia machines

Datex-Ohmeda S5 Aestiva: troubleshooting and error codes

The ServiceForge knowledge base holds 34 documented symptoms for the Datex-Ohmeda S5 Aestiva, with 62 ranked causes, 64 diagnostic checks with test points and expected values, and 0 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

High pressure leak patient safety

Gas leaking from high-pressure system components (O2 outlets, pipelines, valves, cylinders, gauges, gaskets, relief valves)

Ranked causes

1. O2 power outlet leak (unknown)
2. Pipeline leak (unknown)
3. O2 flush valve leak (unknown)
4. System switch leak (unknown)
5. Cylinder not installed properly (unknown)
6. Cylinder gauges leak (unknown)
7. Cylinder gaskets leak (unknown)
8. Relief valves leak (unknown)

First check

Check for leak source

Test point: O2 power outlet, pipeline, O2 flush valve, system switch, cylinders, gauges, gaskets, relief valves
Expected: No leak detected
Tools: Leak detector or Snoop

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

Low pressure leak (with or without vaporizer) patient safety

Gas leaking from low-pressure system components including valves, flush valve, system switch, and flowmeter head

Ranked causes

1. Leaking port valve on vaporizer manifold (unknown)
2. Leaking relief valve on vaporizer manifold (unknown)
3. Leaking flush valve (unknown)
4. Leaking system switch (unknown)
5. Leak at flowmeter head (unknown)
6. Bellows leak (unknown)

First check

Test port valve on vaporizer manifold

Test point: Vaporizer manifold
Expected: No leak
Tools: Vaporizer Manifold Valve Tester

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

Breathing system leak patient safety

Gas leaking from breathing system components such as absorber, canisters, drain, or patient circuit

Ranked causes

1. Absorber drain open (common)
2. Absorber canisters open (common)
3. Soda lime dust on canister seals (unknown)
4. Patient circuit gas sample port open (unknown)
5. Misaligned absorber canisters (unknown)

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

Unable to begin mechanical ventilation patient safety

Machine cannot initiate or enter mechanical ventilation mode

Ranked causes

1. Absorber open (common)
2. Absorber top panel open (unknown)
3. No O2 supply (unknown)
4. Defective Bag/Vent switch (unknown)

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

Bellows leak patient safety

Gas leaking from bellows or bellows-related components due to diaphragm sealing issues, loose mounting, or bellows damage

Ranked causes

1. Pop-off valve diaphragm not sealing properly (unknown)
2. Bellows mounting rim loose (unknown)
3. Bellows improperly mounted or has a hole or tear (unknown)

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

Breathing system leak (intermittent) patient safety

Intermittent gas leaking from breathing system, may be due to misaligned canisters or negative pressure effects

Ranked causes

1. Misaligned absorber canisters (unknown)
2. Main manifold seals open due to negative pressure from gas monitor or patient (unknown)
3. ACGO O2 sense check valve fault (unknown)

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

Low pressure leak (with vaporizer mounted) patient safety

Gas leaking from low-pressure system with vaporizer installed; may be from vaporizer or manifold

Ranked causes

1. Vaporizer not installed properly (unknown)
2. Missing or damaged o-ring on vaporizer manifold (unknown)
3. Loose fill port (unknown)

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

Bellows do not inflate or deflate during mechanical ventilation caution

Bellows remain static or move abnormally during active mechanical ventilation cycle

Ranked causes

1. Bellows mechanical jam or pneumatic circuit blockage (occasional)
2. Ventilator control malfunction (occasional)

First check

Visual inspection of bellows movement

Test point: Bellows
Expected: Bellows inflate and deflate in synchrony with ventilation cycle

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

O2 concentration above minimum during N2O-O2 operation patient safety

When linkage is not engaged, O2 concentration can be increased by reducing N2O flow or increasing O2 flow above engagement point

Ranked causes

1. N2O flow below engagement point (common)
2. O2 flow above engagement point (common)

First check

Observe N2O flow relative to engagement threshold

Test point: N2O flow control position
Expected: At or above kick-in flow (400–700 mL/min)

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

Vaporizer causes excessive back pressure patient safety

Oxygen flow decreases more than 1 L/min when adjusting vaporizer concentration from 0 to 1%

Ranked causes

1. Vaporizer malfunction (common)
2. Aestiva vaporizer manifold port valve defect (occasional)

First check

Measure oxygen flow stability at vaporizer concentration range

Test point: oxygen flow outlet
Expected: O2 flow must not decrease more than 1 L/min, max decrease
Tools: Flow meter, vaporizer

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

Apnea alarm does not occur patient safety

Alarm fails to trigger 30 seconds after disconnection of test lung during mechanical ventilation

Ranked causes

1. Apnea detection or alarm circuit failure (unknown)

First check

Apnea alarm activation timing

Test point: Breath detection circuit
Expected: Alarm occurs after 30 seconds

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

Auxiliary O2 flowmeter ball does not move when flow control rotated patient safety

Flow control ball remains at bottom of tube or does not respond to counterclockwise rotation; may indicate stuck valve or blockage

Ranked causes

1. Flow control valve stuck or damaged (unknown)

First check

Rotate flow control counterclockwise and observe ball movement

Test point: Auxiliary O2 flowmeter tube
Expected: Ball rises immediately and smoothly with rotation

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

Auxiliary O2 flowmeter ball does not rest at bottom when shut off patient safety

Ball remains suspended in tube or does not return to bottom position when flow control fully clockwise; indicates internal leak

Ranked causes

1. Internal leak in flowmeter (unknown)

First check

Occlude auxiliary O2 outlet and observe ball position

Test point: Auxiliary O2 flowmeter outlet
Expected: Ball rests at bottom of flow tube and does not move

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

Calibration: Flow sensor check

Verify raw velocity measurement of inspiratory and expiratory flow sensors and validate flow valve calibration using a test device with ±2.5% accuracy

Ranked causes

1. Flow sensor readings deviate from test device by more than 10% (common)

First check

Remove bellows housing

Test point: Bellows housing
Expected: Housing removed

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

Calibration: O2 Flush Regulator pressure high voltage

O2 Flush Regulator outlet pressure verification and adjustment to specification 131 +0/-7 kPa (19 +0/-1.0 psi)

Ranked causes

1. O2 Flush Regulator pressure out of specification (unknown)

First check

Bleed all gas pressure from the machine

Test point: All cylinder and pipeline gauges
Expected: Zero

3 more checks with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Calibration: O2 Supply Failure Alarm threshold patient safety

O2 Supply Failure alarm adjustment on Induction machine pneumatic assembly; alarm should trigger at correct pressure threshold during O2 supply depletion

Ranked causes

1. O2 Supply Failure alarm threshold drift or miscalibration (occasional)

First check

Measure O2 pressure at which O2 Supply Failure alarm sounds

Test point: O2 primary regulator test port (or plugged 6-mm O2 port on pipeline machines)
Expected: 248 ±7 kPa (36 ±1 psi), ±7 kPa
Tools: Pressure gauge

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

Calibration: Piston-style primary regulator adjustment patient safety

Adjust piston-style regulator output pressure to meet specification (620–634 kPa / 90–92 psi initial, or 607–669 kPa / 88–97 psi for readjustment) by turning the adjustment cap while monitoring regulated pressure under flow conditions.

Ranked causes

1. Regulator output pressure out of specification (unknown)

First check

Slowly open the cylinder valve

Test point: Cylinder valve
Expected: Valve fully open

9 more checks with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

High airway pressure alarm does not occur patient safety

Alarm fails to trigger when peak airway pressure exceeds pressure limit setting

Ranked causes

1. Pressure limit set too high or alarm circuit malfunction (unknown)

First check

High airway pressure alarm occurrence

Test point: Bellows/pressure sensor
Expected: Alarm occurs when Plimit is less than peak pressure

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

High O2 alarm does not occur patient safety

Alarm fails to trigger when O2 concentration exceeds 50% after O2 flush button pressed

Ranked causes

1. O2 sensor malfunction or high O2 alarm circuit failure (unknown)

First check

High O2 alarm occurs at 50% setpoint

Test point: Alarm module
Expected: Alarm occurs when O2 reaches 50%

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

Incorrect battery status message on ventilator display patient safety

Wrong or absent message displayed on ventilator display after power loss

Ranked causes

1. Ventilator model mismatch or display malfunction (occasional)

First check

Verify correct battery status message appears on display after power disconnection

Test point: Ventilator display
Expected: "On Battery - Check Power" for 7900 or "On Battery - Power OK?" for 7100

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

Low airway pressure alarm does not occur patient safety

Alarm fails to trigger when patient connection is disconnected during ventilation

Ranked causes

1. Disconnection detection or alarm circuit failure (unknown)

First check

Low airway pressure alarm when disconnected

Test point: Patient connection
Expected: Alarm occurs after disconnection

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

Low minute volume alarm does not occur when set patient safety

Alarm fails to trigger when low minute volume threshold is activated

Ranked causes

1. Alarm threshold not reached or minute volume measurement failure (unknown)

First check

Low minute volume alarm activation

Test point: Alarms menu
Expected: Alarm occurs at 6.0 L/min setting

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

Low O2 alarm does not occur patient safety

Alarm fails to trigger when O2 concentration drops below 50% setpoint

Ranked causes

1. O2 sensor malfunction or alarm circuit failure (unknown)

First check

O2 sensor reading in room air

Test point: O2 sensor in circuit module
Expected: approximately 21% O2, ±5%

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

Mains indicator not illuminated high voltage

Power cord connected to wall outlet but mains indicator does not come on, indicating no AC power to system

Ranked causes

1. No AC power from wall outlet (common)

First check

Verify mains indicator illuminates when power cord connected

Test point: Mains indicator
Expected: Indicator on when AC power connected

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

Maximum flow limit not functioning caution

CO2 or Heliox flow can be turned beyond maximum stop position, indicating stop collar malfunction

Ranked causes

1. Stop collar tab misalignment or wear (rare)

First check

Turn CO2 or Heliox knob counterclockwise to maximum

Test point: CO2 or Heliox flow control knob
Expected: Knob stops when stop collar tab contacts maximum stop collar tab

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

N2O flow does not decrease with O2 flow patient safety

N2O flow fails to decrease when O2 flow is increased, indicating loss of flow synchronization

Ranked causes

1. Defective pilot regulator (unknown)

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

Positive end expiratory pressure present when PEEP is off caution

Elevated end expiratory pressure measured when PEEP control is set to OFF

Ranked causes

1. Scavenging system insufficient gas removal (common)

First check

Measure end expiratory pressure at O2 flow 5 L/min with PEEP OFF

Test point: Ventilator display
Expected: approximately 0 cm H2O

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

Power failure alarm does not activate patient safety

When AC power is disconnected with system on, no alarm sounds and battery status message does not appear on ventilator display

Ranked causes

1. Power failure detection circuit malfunction (unknown)

First check

Mains indicator illumination

Test point: Front panel mains indicator
Expected: Indicator on when AC power connected

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

Power failure alarm does not cancel after reconnection caution

Power failure alarm continues after power cable is reconnected

Ranked causes

1. Alarm cancellation circuit malfunction (rare)

First check

Reconnect power cable and verify alarm cancels

Test point: Power failure alarm
Expected: Alarm silences after power cable reconnected

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

Regulator output pressure exceeds specification patient safety

Regulator output pressure is too high. Decrease the adjustment cap and readjust within specification range.

Ranked causes

1. Adjustment cap set too high (unknown)

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

Subatmospheric pressure alarm occurs during ventilation patient safety

Alarm triggers when mechanical ventilation is active with O2 flow at minimum

Ranked causes

1. Excessive gas scavenging flow (common)

First check

Verify mechanical ventilation starts and no subatmospheric alarm occurs

Test point: Bellows
Expected: Bellows inflate and deflate, no alarm

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

Sustained airway pressure alarm does not occur patient safety

Alarm fails to trigger when closed patient connection and O2 flush button is pressed

Ranked causes

1. Alarm circuit malfunction or timer failure (unknown)

First check

Sustained airway pressure alarm occurrence

Test point: Pressure sensor/alarm module
Expected: Alarm occurs after approximately 15 seconds at sustained pressure limit (6-30 cm H2O)

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

Unit displays low O2 pressure with pipeline but not with cylinders patient safety

Low O2 pressure alarm displayed when using pipeline supply but not when using cylinder supply

Ranked causes

1. Low O2 supply switch fault (unknown)

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

Ventilator does not display correct data caution

Ventilator display shows incorrect tidal volume, rate, or other parameters during mechanical ventilation

Ranked causes

1. Ventilator calculation or display malfunction (unknown)

First check

Ventilator displays correct tidal volume

Test point: Ventilator display
Expected: 400 ml

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

Community

0 fixes logged by technicians through their AI, with outcomes, for this model.

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