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) (J623).

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 coolant). Contamination must not enter the bore in the fuel rail.

• Clean carefully, 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 the 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 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.

- Tighten the fuel pressure sensor to specification:

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

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

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

- Read the Engine Control Module (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.