Cummins ISB CM850 (2003-06) Fault Code: 449 (ISC – Auto) PID: 94 SPN: 157 FMI: 0 Injector Metering Rail Number 1 Pressure – Data Valid But Above Normal Operating Range – Most Severe Level. Fuel pressure signal indicates that fuel pressure has exceeded the maximum limit for the given engine rating. Fault Code 449 is activated when the sensed rail fuel pressure exceeds the opening pressure of the rail fuel pressure relief valve. In normal engine operation the ECM calibration varies the flow command to the fuel pump actuator to achieve the correct fuel rail pressure. System failures that cause...

Cummins ISB CM850 (2003-06) Fault Code: 451 PID: 157 SPN: 157 FMI: 3 Injector Metering Rail Number 1 Pressure Sensor Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at rail fuel pressure sensor circuit. This fault code will become active if there is an open circuit on any of the three pins (+5 volt SUPPLY, SIGNAL, and RETURN) that connect the sensor or the ECM to the wiring harness. This fault will also be active if the SIGNAL wire is shorted to a source of voltage. This fault code will become inactive any time...

Cummins ISB CM850 (2003-06) Fault Code: 452 PID: 157 SPN: 157 FMI: 4 Injector Metering Rail Number 1 Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the rail fuel pressure sensor circuit. This fault code will become inactive any time the keyswitch is ON and the SIGNAL pin voltage of the ECM is too low. This can be caused by a short circuit to ground on the +5-VDC SUPPLY or SIGNAL wire. This fault will also become active if a device that is powered by the common +5-VDC power supply is...

Cummins ISB CM850 (2003-06) Fault Code: 471 PID: 98 SPN: 98 FMI: 17 Engine Oil Level ? Data Valid But Below Normal Operational Range ? Least Severe Level. Low oil level has been detected by the oil level sensor. If inactive counts of Fault 471 are logged in the ECM, it could be possible that the engine was running or keyed on while tilted at an angle severe enough to cause this fault to be triggered. Other causes of fault code 471 may include: 1)The engine may not have been filled to proper capacity during the most recent oil change2)External...

Cummins ISB CM850 (2003-06) Fault Code: 488 PID: 105 SPN: 105 FMI: 0 Intake Manifold 1 Temperature – Data Valid but Above Normal Operational Range – Moderately Severe Level. Intake manifold air temperature signal indicates intake manifold air temperature above engine protection warning limit. The intake manifold air temperature sensor measures the temperature of the charge-air as it passes through the intake manifold. Possible causes: 1)Plugged charge air cooler fins2)Restricted airflow through the charge air cooler3)Undersized charge air cooler4)High turbocharger compressor outlet temperature. Possible repairs: 1)Replace the intake manifold air temperature sensor. Cummins ISB CM850 (2003-06) Fault Code: 471 PID:...