Cummins ISB CM850 (2003-06) Fault Code: 271 (ISC – Auto) PID: SID 126 SPN: 1347 FMI: 4 High Fuel Pressure Solenoid Valve Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the fuel pump actuator circuit.

Posted by PerDiezel Solutions on January 18, 2026

This fault becomes active when the ECM detects a short circuit in the electronic fuel control actuator circuit. Causes for this fault code are short circuit to ground or low resistance (fuel control actuator coil is shorted internally) in the circuit for the fuel pump actuator. When excessive current or a short circuit is detected, the ECM driver to the fuel control actuator is turned off to protect the circuit. It is necessary to cycle the keyswitch off and then back on before the ECM will retest for the cause of the fault code. The ECM driver is reenabled at key-on; and if the cause is no longer present, the fault code will become inactive and can be cleared. If the fault code is intermittent, look for causes of an intermittent short to ground in the wiring harness or connectors. Since the ISC and ISL engines utilize a 2-stage fuel rail pressure relief valve, failures to the fuel pump actuator will result in operation with the fuel rail pressure relief valve open. Extended operation with the fuel rail pressure relief valve open can damage the pressure relief valve.

Fault Code 2311 may have high counts if the fault condition is or was intermittent.

Possible repairs:

1)Replace the fuel pump actuator.
2)Repair the damaged harness, connector, or pins if possible.
3)Repair or replace the engine harness.
4)Replace the ECM.

Cummins ISB CM850 (2003-06) Fault Code: 271 (Auto) PID: SID 126 SPN: 1347 FMI: 4 High Fuel Pressure Solenoid Valve Circuit – Voltage Below Normal or Shorted to Low Source. Electronic fuel control actuator shorted low.

Cummins ISB CM850 (2003-06) Fault Code: 269 PID: SID 217 SPN: 1195 FMI: 2 Antitheft Password Valid Indicator ? Data Erratic, Intermittent, or Incorrect. Engine ignition attempt without authorization from immobilizer anti-theft device.

Cummins ISB CM850 (2003-06) Fault Code: 268 PID: 94 SPN: 94 FMI: 2 Injector Metering Rail 1 Pressure – Data Erratic, Intermittent, or Incorrect. The ECM has detected that the fuel pressure signal is not changing.

Cummins ISB CM850 (2003-06) Fault Code: 253 PID: 98 SPN: 98 FMI: 1 Engine Oil Level ? Data Valid But Below Normal Operational Range ? Most Severe Level. Very low oil level has been detected by the oil level sensor.

Cummins ISB CM850 (2003-06) Fault Code: 245 PID: SID 33 SPN: 647 FMI: 4 Fan Control Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the fan control circuit when commanded on.

Cummins ISB CM850 (2003-06) Fault Code: 242 PID: 84 SPN: 84 FMI: 10 Vehicle Speed Sensor Circuit Tampering Has Been Detected – Abnormal Rate of Change. Invalid or inappropriate vehicle speed signal. Signal indicates an intermittent connection or VSS tampering.

WARNING!