Cummins ISB CM850 (2003-06) Fault Code: 1675 PID: SPN: 3249 FMI: 3 Exhaust Gas Temperature 2 Circuit ? Voltage Above Normal, or Shorted to Low Source. High signal voltage detected at the catalyst outlet temperature sensor circuit. Catalyst outlet temperature sensor shares return wires in the engine harness with other sensors. A shorted return can cause multiple fault codes to be active. Possible causes: 1)Open return circuit in the harness, connectors, or sensor.2)Open signal circuit or shorted to a voltage source. On-Board Diagnostics (OBD) Information (Euro 4 Certified Engines): 1)The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic...

Cummins ISB CM850 (2003-06) Fault Code: 1676 PID: SPN: 3249 FMI: 2 Exhaust Gas Temperature 2 ? Data Erratic, Intermittent, or Incorrect. The exhaust gas temperature #2 sensor is not changing with engine operating conditions. This diagnostic runs when the exhaust gas temperature sensors are compared to other engine temperatures during engine operation. The engine coolant temperature must be above 140?F before the diagnostic will run. If the value of the exhaust gas temperature #2 does not match the engine operating conditions, this fault code is logged. Possible causes: 1)Stuck in-range exhaust gas temperature #2 sensor2)High resistance in the exhaust...

Cummins ISB CM850 (2003-06) Fault Code: 1677 PID: SPN: 3031 FMI: 4 Catalyst Tank Temperature ? Voltage Below Normal, or Shorted to Low Source. Low signal voltage detected at the catalyst solution temperature sensor circuit. The catalyst solution temperature sensor shares return wires in the engine harness with other sensors. A shorted return can cause multiple fault codes to be active. Before troubleshooting Fault Code 1677, check for multiple fault codes. Possible causes: 1)Signal shorted to ground in the harness2)Signal shorted to return or ground in the sensor. On-Board Diagnostics (OBD) Information (Euro 4 Certified Engines): 1)The ECM illuminates the...

Cummins ISB CM850 (2003-06) Fault Code: 1678 PID: SPN: 3031 FMI: 3 Catalyst Tank Temperature ? Voltage Above Normal, or Shorted to High Source. High signal voltage or open circuit detected at the catalyst tank temperature sensor circuit The catalyst solution temperature sensor shares return wires in the engine harness with other sensors. An open return can cause multiple fault codes to be active. Possible causes: 1)Open return circuit in the harness, connectors, or sensor.2)Open signal circuit or shorted to a voltage source. On-Board Diagnostics (OBD) Information (Euro 4 Certified Engines): 1)The ECM illuminates the malfunction indicator lamp (MIL) when...

Cummins ISB CM850 (2003-06) Fault Code: 1679 PID: SPN: 3031 FMI: 2 Catalyst Tank Temperature ? Data Erratic, Intermittent, or Incorrect. The catalyst solution temperature sensor is not changing with engine operating conditions. This diagnostic runs when the engine has not been running for at least eight hours. The catalyst solution temperature sensor is compared to engine coolant temperature and intake manifold temperature when the key is turned on after the extended eight hour shutdown. This fault code is logged if the reading from the catalyst solution temperature sensor does not match the readings from engine coolant temperature and intake...