Fuel Pressure Sensor/Switch: Service and Repair

Fuel Pressure Sensor

The fuel pressure sensor (G247) is located in the left fuel rail (high pressure reservoir) for cylinder bank 2. It measures the current fuel pressure in the high pressure system and delivers a voltage signal to the diesel direct fuel injection Engine Control Module (ECM) (J248).

If the sensor malfunctions, the pressure is controlled via an ECM characteristic map. The maximum engine speed is limited to approximately 3000 RPM in emergency mode.

The fuel pressure sensor cannot be reused.

Removing

CAUTION!
Follow the guidelines for clean working conditions when working on the fuel system. Refer to => [ Clean Working Conditions and Fuel System Work Instructions ] Clean Working Conditions and Fuel System Work Instructions.

Always follow these instructions before and during work.

- Remove the engine cover.

- Before removing, clean the threaded area around the fuel pressure sensor using a commercially available detergent. Dirt must not enter the hole in the high pressure reservoir.

• Clean carefully, cleaner must not enter the connector.

- Dry the fuel pressure sensor.

- Disconnect the connector from the fuel pressure sensor.

- Remove the fuel pressure sensor.

- Suction any dirt out of the hole in the fuel rail, the threads and the sealing surface. Do not use mechanical tools.

• Seal the hole in the fuel rail immediately with a suitable plug to prevent dirt from entering.

Installing

• The fuel pressure sensor does not have seal. It has a biting edge and cannot be reused.

• Check the sealing surfaces and threads on the new fuel pressure sensor for damage.

• Check the sealing surface on the hole in the fuel rail.

• The fuel pressure sensor threads are lubricated with an anti-friction coating so they must be free of oil and grease.

- Tighten the fuel pressure sensor by hand.

- Tighten the sensor to 70+/-5 Nm.

- After installing, let the engine run at a moderate speed for a few minutes and then shut it off.

- Check fuel system for leaks.

- Check the Diagnostic Trouble Code (DTC) memory. Refer to => [ Engine Control Module DTC Memory, Checking and Erasing ] Scan Tool Testing and Procedures.

- Perform a road test where the accelerator pedal is pressed all the way down at least one time. Then check the high pressure area again for leaks.

- Check the DTC memory again. Refer to => [ Engine Control Module DTC Memory, Checking and Erasing ] Scan Tool Testing and Procedures.