Oximeters · INVOS family

Covidien INVOS 5100C: troubleshooting and error codes

The ServiceForge knowledge base holds 21 documented symptoms for the Covidien INVOS 5100C, with 51 ranked causes, 25 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

No rSO2 reading displayed patient safety

System does not display oxygen saturation values; sensor or preamplifier signal not received

Ranked causes

1. Error messages displayed; follow on-screen instructions (common)
2. Preamplifier not connected to monitor, sensor cable or sensor (common)
3. Sensor not applied to patient (common)
4. System locked up (occasional)
5. Defective CPU (occasional)
6. Defective preamplifier cable or connector (occasional)
7. Blown fuse on DIB (occasional)
8. Defective preamplifier (rare)

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

Unit does not power up high voltage

System fails to turn on completely; no display or lights

Ranked causes

1. No AC power to outlet (common)
2. Blown fuse on line filter (common)
3. Blown fuse on power supply (occasional)
4. Secondary power cable disconnected or keypad connector not seated (occasional)
5. Blown fuse on DIB (occasional)
6. Defective CPU board (rare)

First check

Verify AC power is available at outlet

Test point: Hospital-grade electrical outlet
Expected: AC power present

2 more checks with pass and fail actions, 6 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Keypad does not function

Buttons do not respond to key presses; no input accepted from control panel

Ranked causes

1. Defective keypad (common)
2. System locked up (common)
3. Internal cable not connected (occasional)
4. Defective DIB (occasional)

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

No battery power available

System cannot operate on battery backup; battery does not provide power

Ranked causes

1. Defective battery (common)
2. Defective DIB (occasional)
3. Internal cable not connected or keypad connector not seated (occasional)
4. Blown fuse on DIB (occasional)

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

Signal Strength Indicator (SSI): 1-4 bars fluctuating and unstable patient safety

SSI display shows weak, unstable signal with rapid fluctuations; rSO2 reading reliability degraded

Ranked causes

1. Signal interference from external sources (common)
2. Sensor applied over anatomical anomalies or contaminants (common)
3. Defective SomaSensor (occasional)
4. Moisture in sensor connection (occasional)

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

Calibration: INVOS 5100C System high voltage

Factory-calibrated system requires annual inspection and functional verification. System calibration is set during manufacturing and stored in SomaSensor chip. Includes mechanical and electrical inspection points.

Ranked causes

1. Annual inspection required per maintenance schedule (common)
2. Functional test with adjustable field test device (common)
3. Battery backup replacement after 5 years (occasional)

First check

Inspect chassis and cables for physical damage

Test point: Power cord, sensor cables, preamplifiers, battery status, chassis screws, key panel, fan, internal components
Expected: No loose screws, cracks, dirt, loose connectors or damaged cords

13 more checks with pass and fail actions, 12 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Display is not visible

LCD display is dark or blank; no visible text or images

Ranked causes

1. Internal cables not properly seated (common)
2. Defective LCD (occasional)
3. Defective backlight lamp on LCD (occasional)

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

No display visible

Screen is completely dark; no LCD output at all

Ranked causes

1. Defective CPU (occasional)
2. Defective display (occasional)
3. Defective inverter board (occasional)

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

Unit locks up or operates erratically

System freezes, intermittently crashes, or behaves unpredictably during operation

Ranked causes

1. Erratic AC power input (common)
2. Defective CPU board (occasional)
3. Defective DIB (occasional)

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

Digital output: COM port unavailable message

Error message displayed when selecting CASE HISTORY in DIGITAL OUTPUT menu; no PC connection established

Ranked causes

1. Digital output port not connected to PC with null modem cable (common)
2. Wrong COM port specified in Hyper Terminal (common)

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

Display does not show expected rSO2 values

When testing with Adjustable Field Test Device set to known values (90, 70, 50, 30), the display either does not show the value or shows out-of-range data on connected channels

Ranked causes

1. Monitor requires alignment and testing with Field Test Device (unknown)

First check

Verify rSO2 display matches Field Test Device setting

Test point: Main Screen display
Expected: rSO2 value of 90, 70, 50, or 30 ±1 or poor sensor signal indication

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

Display is on but green light is not on

LCD display functions but power indicator light not illuminated

Ranked causes

1. Defective keypad (common)

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

External monitor display mismatch

External monitor screen does not match INVOS 5100C Monitor screen during final functional test

Ranked causes

1. Serial or USB connection failure (unknown)

First check

Verify external monitor displays same screen as INVOS 5100C Monitor

Test point: External Monitor connected via serial interface
Expected: External monitor screen identical to INVOS 5100C Monitor

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

Line leakage current test failure high voltage

Red FAIL light turns on and alarm sounds during line leakage testing; failure mode displayed on tester front panel

Ranked causes

1. Safety ground or neutral/reverse fault condition exceeded (unknown)

First check

Monitor line leakage current through eight test configurations

Test point: INVOS 5100C Monitor with Line Leakage Tester connected
Expected: All eight SFC and NC configurations pass with current within limits

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

Lithium battery replacement on CPU

Coin-type lithium battery supplies real-time clock circuit. Nominal 3-3.3VDC, service life approximately 5-6 years at 20°C ambient.

Ranked causes

1. Lithium battery end-of-life after 5-6 years service (occasional)

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

No connectivity with Philips module

System cannot establish or maintain connection with Philips equipment; digital output not working

Ranked causes

1. Output mode switched from Printer/PC Link to Philips without restart (common)

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

No data received or transmission scrambled

Digital output data missing or corrupted; cannot receive or view transmitted data

Ranked causes

1. Hyper Terminal settings not correct (common)

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

Power-on LEDs not illuminated high voltage

PWR ON (green) LED or AC Power (blue) LED not lit after pressing On/Off button

Ranked causes

1. AC power not connected or power supply fault (common)

First check

Verify AC power cable connected and both indicator LEDs lit

Test point: INVOS 5100C Monitor back panel AC input and front panel LEDs
Expected: PWR ON (green) LED and AC Power (blue) LED both illuminated

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

Preamplifier AC Withstand Voltage (Hipot) test failure high voltage

Alarm sounds and red RESET light turns on during Hipot testing, indicating preamplifier failed electrical safety test

Ranked causes

1. Preamplifier isolation or insulation breakdown at 1800V (unknown)

First check

Verify AC Withstand Voltage Tester display parameters

Test point: Tester front panel display
Expected: SET M2 1.0s 1.8KVAC 1.00mA

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

Saturation value out of range after power-up patient safety

Oximeter saturation reading is not constant or falls outside 47% to 53% range on display during initial verification

Ranked causes

1. Hardware defect or sensor simulator fixture malfunction (unknown)

First check

Verify saturation value is constant and within range

Test point: INVOS 5100C Monitor display with Sensor Simulator Fixture connected to Preamplifier
Expected: Saturation value constant between 47% and 53%

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

Signal Strength Indicator (SSI): 0 bar patient safety

SSI shows no bars; signal is completely lost; rSO2 value not displayed

Ranked causes

1. Error condition; see error messages on display (unknown)

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.