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 (VAG 1331)

• Vehicle diagnosis, testing and information system (VAS 5051B)

• Pressure sensor tester (VAS 6394)

• 27 mm socket (VAS 5301/7)

• Test instrument adapter/DSO (3-pin) (VAS 5570)

Test Sequence

• Fuel rail assembly overview. Refer to --> [ Fuel Rail Assembly Overview ] Fuel Rail Assembly Overview.

- Read the safety precautions before beginning work. Refer to --> [ Safety Precautions ] Safety Precautions.

- Observe the rules for cleanliness. Refer to --> [ Clean Working Conditions ] Clean Working Conditions.

CAUTION!
Fuel system is under pressure! Before opening high pressure components of the fuel injection system, the fuel pressure must be relieved to residual pressure, procedures. Refer to --> [ High Side Fuel Pressure Releasing ] High Side Fuel Pressure Releasing.

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

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

- Lubricate the (VAS 6394/2) sealing point with clean engine oil and install it in the fuel rail.





• Tightening specification: 22 Nm.

- Remove the locking bolt - 2 - and install the fuel pressure sensor to the (VAS 6394/1).





• Tightening specification: 22 Nm.

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

- Connect the fuel pressure sensor and its connector to the (VAS 5570).





- Switch the (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 (VAS 6394/1) does not display 0 bar, set it back to zero, refer to --> operating instructions.

- Connect the vehicle diagnosis, testing and information system (VAS 5051B) - 1 - as follows:





- Connect the diagnostic cable - 2 - to the Data Link Connector (DLC) in the driver footwell.

- Switch on the ignition.

- On the following screens, select:

Vehicle Self-Diagnosis

01 - Engine Electronics >

011 - Measured Values >

- Select the measured value block 1 4 0 and confirm with the Q button.

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

- Start the engine and let run at idle.

- Compare the pressure displayed by the (VAS 6394/1) with the actual value displayed on the (VAS 5051B).

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

CAUTION!
The (VAS 6394/1) 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. Switch off the ignition. Place a cloth around the fuel pressure sensor , then carefully loosen the fuel pressure sensor to release the remaining pressure.

Difference greater than 5 bar:

- Replace the fuel pressure sensor.

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

If the measured value do not match again:

- Check the wiring using the "Guided Fault Finding".