Fuel Pressure Sensor: Testing and Inspection

Fuel Pressure Sensor, Checking

Special tools, testers and auxiliary items required

• Assembly Tool (T10118)

• Torque Wrench (5-50 Nm) (V.A.G 1331)

• Vehicle Diagnostic Tester, for example, (VAS 5051 B)

• Pressure Sensor Tester (VAS 6394)

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

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

Procedure

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

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

- Coat the adapter (VAS 6394/2) sealing point with clean engine oil and install it in the fuel rail. Tightening specification: 27 Nm.






- Remove the locking bolt - 2 - and install the fuel pressure sensor in the pressure sensor tester (VAS 6394/1). Tightening specification: 27 Nm.






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

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






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






• Holding the button - A - for 2 seconds turns 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 the ignition on.

- 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 actual value fuel pressure 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 diagnostic tester.