Fuel Pressure Sensor/Switch: Service and Repair

Fuel Pressure Sensor G247

Function

The fuel pressure sensor (rail pressure sensor) is located in the fuel rail. It measures the current fuel pressure in the high pressure system and delivers a voltage signal to the Engine Control Module (ECM).

If the fuel pressure sensor malfunctions, the pressure is controlled via a ECM characteristic map (maximum engine speed is limited to approximately 3000 RPM in emergency operation mode).

Special tools, testers and auxiliary items required

• Torque Wrench (40-200 Nm) (V.A.G 1332)


• Follow the safety precautions when working on the diesel direct injection system. Refer to => [ Safety Precautions ] Diesel Fuel Injection.

• Observe the rules for cleanliness. Refer to => [ Clean Working Conditions ] Diesel Fuel Injection.

Always follow these instructions before and during work.

Removing

- Remove the engine cover. Refer to => [ Engine Cover ] Engine Cover.

- Before removing, clean the threaded area around the fuel pressure sensor (for example using commercially available detergent). Contamination must not enter the bore in the fuel rail.

• Clean carefully, the cleaner must not enter the connector.

- Dry the fuel pressure sensor.

- Disconnect the connector from the fuel pressure sensor - C -.






- Remove the fuel pressure sensor.

- Extract any contamination from the fuel rail bore (threads and sealing surface). Do not use mechanical tools.

• Seal the fuel rail bore immediately with a suitable plug to prevent contaminants from entering.

Installing

• Check the fuel pressure sensor sealing surface and threads for damage.

• Check the sealing surface on the fuel rail bore.

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

- First, tighten the fuel pressure sensor by hand.

- Then, tighten the fuel pressure sensor to specification:

• Tightening specification, see - item 14 - in the => [ Fuel Rail and Injectors Overview ] Service and Repair.

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

- Check the fuel system for leaks. Refer to => [ Fuel System, Leak Test ] Fuel System, Leak Test.

- Read the ECM Diagnostic Trouble Code (DTC) memory again. Refer to "Guided Functions" in the vehicle diagnostic tester.

- Install the engine cover. Refer to => [ Engine Cover ] Engine Cover.