Fuel Pressure Sensor: Testing and Inspection

Fuel Pressure Sensor (G247), Checking

Special tools, testers and auxiliary items required

• Assembly tool (T10118)

• Double Hexagon Socket, 1/2 inch, 27 mm (VAS 5301/7)

• Pressure Sensor Tester (VAS 6394)

• Test Instrument Adapter/DSO (3-Pin) (VAS 5570)

Procedure


• The fuel pressure sensor is under pressure. Always wear protective eye-wear and protective clothing to prevent injuries and fuel from coming in contact with your skin. Wrap a cloth around the connection point before loosening the fuel pressure sensor. Then release pressure by carefully loosening.

- Remove the fuel pressure sensor. Refer to => [ Fuel Pressure Sensor (G247) ] Service and Repair.

- Remove the locking bolt - 2 - and install the fuel pressure sensor into the pressure sensor tester (VAS 6394/1). Tightening specification: 22 Nm.






- Lubricate the adapter (VAS 6294/2) sealing point with clean engine oil and install it in the fuel rail. Tightening specification: 22 Nm.






- Connect the pressure sensor tester (VAS 6394/1) line to the adapter (VAS 6394/2).






- Connect the fuel pressure sensor - 1 - to the fuel pressure sensor connector using the test instrument adapter/DSO (3-pin) (VAS 5570).

- Install the engine cover/upper air filter housing and connect the mass airflow sensor (G70).

- Turn the pressure sensor tester (VAS 6394/1) on by pressing the button - A - briefly.






• Holding the button - A - for 2 seconds switches on the illumination for 20 seconds.

• If the pressure sensor tester (VAS 6394/1) does not display 0 bar, set it back to zero. Refer to the operating instructions.

- Connect the vehicle diagnostic tester to the diagnostic connector.

- Turn on the ignition.

- Press the following buttons on the vehicle diagnostic tester screen one after another.

OBD

OBD =>

01 - engine electronics =>

011 - measured values =>

- Select measured values block 1 4 0 and confirm with Q.

Display field 3 shows the fuel pressure actual value as measured by the fuel pressure sensor.

- Start the engine.

- Compare the pressure displayed by the pressure sensor tester (VAS 6394/1) with the actual value displayed on the vehicle diagnostic tester.

• The pressures may have a maximum difference of 5 bar.

- If the difference is greater than 5 bar, replace the fuel pressure sensor.


The pressure sensor tester (VAS 6394) is under high fuel pressure. Disconnect the connector from the fuel pressure sensor when the engine is running. This reduces the pressure to approximately 6 bar. Turn off the ignition. Place a cloth around the fuel pressure sensor, then carefully loosen the sensor to release the remaining pressure.

- Repeat the test with the new fuel pressure sensor and compare both measured values.

If the measured value do not match again:

- Perform a wiring test. Refer to the vehicle diagnosis, testing and information system VAS 5051.