Cummins ISB CM850 (2003-06) Fault Code: 436 PID: 105 SPN: 105 FMI: 2 Intake Manifold 1 Temperature – Data Erratic, Intermittent, or Incorrect. The intake manifold temperature sensor is reading an erratic value at initial key ON.

Posted by PerDiezel Solutions on January 18, 2026

The engine intake manifold temperature is compared to the engine coolant temperature and catalyst inlet temperature at initial key ON. The ECM must not see engine speed for a period of eight hours before this diagnostic will run. If the value of engine intake manifold temperature does not match the temperature readings from the engine coolant temperature and the catalyst inlet temperature within a pre-defined tolerance, this fault code is logged.

Possible causes:

1)Stuck in-range engine intake manifold temperature sensor reading.
2)High resistance in the engine intake manifold temperature sensor SIGNAL or RETURN wires.

On-Board Diagnostics (OBD) Information (Euro 4 and Euro 4 Stage 1+ Certified Engines):

1)The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2)The ECM turns OFF the MIL after three consecutive ignition cycles that the diagnostic runs and passes. The MIL and fault code can also be cleared using INSITE? electronic service tool.
3)The fault code will be cleared from memory after 40 consecutive drive cycles where the diagnostic runs and passes.

The sensor return configuration for Euro 4 ISB engines has been changed for automotive wiring harnesses manufactured from February 2012 onward. The new style wiring harnesses can be be identified using the method below:

1)Disconnect the ECM connector
2)Disconnect the camshaft position sensor
3)Disconnect the intake manifold pressure/temperature sensor
4)Check for continuity between the intake manifold pressure/temperature sensor RETURN pin, and the camshaft position sensor RETURN pin
5)Check for continuity between ECM pin 47 and the camshaft position sensor RETURN pin
6)Use the table below to determine which harness is fitted to the engine.

NOTE: QSB engines, all C series engines, and all L series engines are not affected by this change.

Possible repairs:

1)Clean the connector and pins.
2)Replace the engine intake manifold temperature sensor.
3)Repair or replace the engine harness.
4)Replace the ECM.

Cummins ISB CM850 (2003-06) Fault Code: 435 PID: 100 SPN: 100 FMI: 2 Oil Pressure Switch Sensor Circuit – Data Erratic, Intermittent or Incorrect. An error in the engine oil pressure switch signal was detected by the ECM.

Cummins ISB CM850 (2003-06) Fault Code: 434 PID: SID 251 SPN: 627 FMI: 2 Power Supply Lost With Ignition On – Data Erratic, Intermittent or Incorrect. Supply voltage to the ECM fell below 6.2 VDC momentarily, or the ECM was not allowed to power down correctly (retain battery voltage for 30 seconds after key OFF).

Cummins ISB CM850 (2003-06) Fault Code: 433 PID: 102 SPN: 102 FMI: 2 Intake manifold pressure sensor circuit – data incorrect. An error in the intake manifold pressure sensor signal was detected by the ECM.

Cummins ISB CM850 (2003-06) Fault Code: 432 PID: SID 230 SPN: 558 FMI: 13 Accelerator Pedal or Lever Idle Validation Circuit – Out of Calibration. Voltage at idle validation on-idle and off-idle circuit does not match accelerator pedal position.

Cummins ISB CM850 (2003-06) Fault Code: 431 (SSS) PID: SID 230 SPN: 558 FMI: 2 Accelerator Pedal or Lever Idle Validation Circuit – Data Erratic, Intermittent or Incorrect. Voltage detected simultaneously on both idle validation and off-idle validation switches.

Cummins ISB CM850 (2003-06) Fault Code: 431 (NISS) PID: SID 230 SPN: 558 FMI: 2 Accelerator Pedal or Lever Idle Validation Circuit – Data Erratic, Intermittent, or Incorrect. Voltage detected simultaneously on both idle validation and off-idle validation switches.

WARNING!