Cummins ISB CM850 (2003-06) Fault Code: 2266 PID: SID 126 SPN: 1075 FMI: 4 Electric Lift Pump for Engine Fuel Supply Circuit – Voltage Below Normal, or Shorted to Low Source. Low signal voltage detected at the fuel lift pump circuit.

Posted by PerDiezel Solutions on January 18, 2026

This fault code becomes active whenever the ECM detects a short circuit to ground or high current in the electric lift pump circuit. Causes for this fault code are short circuit to ground or low resistance.

On 12 VDC Automotive and 24 VDC Industrial or Marine systems during cold weather, gelled fuel can plug the lift pump and cause this fault code. Listen to the lift pump to be sure it is running during cold ambient temperatures (less than -29?C [-20?F]). This fault code can also become active if the lift pump rotor stalls or seizes. When the fault conditions are detected, the ECM driver to the lift pump 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 re-enabled at keyswitch ON, and if the cause is no longer present, the fault code will become inactive and can be cleared.

On 24 VDC Automotive systems, the ECM driver to the lift pump relay is turned off when a short circuit to ground or high current in the electric fuel lift pump wiring harness relay circuit is detected. Causes of this fault code are a short circuit to ground or high current in the electric fuel lift pump wiring harness, relay or engine harness. This fault code will not become active if the voltage regulator or electric fuel lift pump has failed.

NOTE: On 12 VDC systems, this fault code will also become active if the priming pump motor stalls. Stall current for the priming pump motor is approximately 9 amperes. A good priming pump typically runs with less than 3 amperes. If the fault code is intermittent, observe the snapshot data priming pump measured current. If current was near 9 amperes when the fault condition occurred, conclude that the rotor has stalled and replace the electric priming pump.

Possible repairs:

1)Replace the electric fuel lift pump relay.
2)Removal and installation of the connector may correct the problem.
3)Repair or replace the engine harness.
4)Replace the ECM.

Cummins ISB CM850 (2003-06) Fault Code: 2265 PID: SID 126 SPN: 1075 FMI: 3 Electric Lift Pump for Engine Fuel Supply Circuit – Voltage Above Normal, or Shorted to High Source. High voltage or open detected at the fuel lift pump signal circuit.

Cummins ISB CM850 (2003-06) Fault Code: 2249 PID: 157 SPN: 157 FMI: 1 Injector Metering Rail 1 Pressure – Data Valid but Below Normal Operational Range – Most Severe Level. The ECM has detected that fuel pressure is lower than commanded pressure.

Cummins ISB CM850 (2003-06) Fault Code: 2217 PID: SID 240 SPN: 630 FMI: 111 Engine Control Module Calibration Program Memory (RAM) Corruption – Condition Exists. Severe loss of data from the ECM.

Cummins ISB CM850 (2003-06) Fault Code: 2216 (ISC) PID: 94 SPN: 94 FMI: 1 Fuel Pump Delivery Pressure High – Data Valid but Above Normal Operational Range – Moderately Severe Level. The ECM has detected that fuel pressure is higher than commanded pressure.

Cummins ISB CM850 (2003-06) Fault Code: 2216 (ISB) PID: 94 SPN: 94 FMI: 0 Fuel pump delivery pressure – data valid but above normal operational range – moderately severe level. The ECM has detected fuel pressure in the fuel rail that is higher than the commanded pressure.

Cummins ISB CM850 (2003-06) Fault Code: 2215 (ISC) PID: 94 SPN: 94 FMI: 0 Fuel Pump Delivery Pressure Low – Data Valid but Below Normal Operational Range – Moderately Severe Level. The ECM has detected that fuel pressure is lower than commanded pressure.

WARNING!