CM850 Electronic Control System – FAULT CODE 268

Injector Metering Rail 1 Pressure – Data Erratic, Intermittent, or Incorrect


Fault Code: 268
PID: P094
SPN: 94
FMI: 2
LAMP: Amber

Injector Metering Rail 1 Pressure – Data Erratic, Intermittent, or Incorrect. The ECM has detected that the fuel pressure signal is not changing.

The ECM will estimate fuel pressure, and power is reduced.

Fuel Pressure Sensor Circuit

Circuit Description

The fuel pressure sensor contains supply, signal, and return pins. The ECM provides +5 VDC to the fuel pressure sensor. This +5 VDC power supply is a shared supply. Other sensors on this circuit are the intake manifold pressure sensor, backup engine position sensor.

Component Location

The fuel pressure sensor is located in the rail fuel on the air intake side of the engine. See Procedure Refer to Procedure 100-002 for a detailed component location view.

Shop Talk

This fault code can become active any time the engine is loaded and the ECM detects that fuel pressure in the rail fuel is not changing. This fault code will become inactive whenever the ECM is powered down or if the ECM detects that the engine is loaded and the fuel pressure is changing normally. If there are many inactive counts of this fault code or if the fault is not repeatable, look for signs of tampering to the fuel pressure sensor circuit. If the fault code occurs intermittently (can not
be reproduced during a road test), then inspect each of the following for poor connections or damage:

  • Intake manifold pressure sensor
  • Backup engine position sensor
  • Fuel pressure sensor.

Refer to Troubleshooting Fault Code t05-268

Last Modified:  08-Jul-2010