Fuel Injection and Ignition

Fuel Pressure Sensor (G247), Checking

Special tools, testers and auxiliary items required

• Pressure Sensor Tester (VAS 6394)

• Pressure Sensor Tester (VAS 6394/1)

• Adapter (VAS 6394/2)

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

• Torque Wrench 5-50 Nm (V.A.G 1331)

• Vehicle Diagnostic Tester

Procedure

- Remove the engine cover.

Fuel system is under pressure! Fuel pressure must be reduced to a residual pressure before opening the high pressure area of injection system. Refer to => [ Releasing Pressure in High Pressure Area ] Releasing Pressure In High Pressure Area.

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

- In place of the fuel pressure sensor install the (VAS 6394/2) and tighten it using the tightening specification for the fuel pressure sensor.






• Tightening specifications: Fuel rail assembly overview, refer to => [ Fuel Rail Overview ] Fuel Rail Overview

- Remove the plug - 2 - on the (VAS 6394) , install the fuel pressure sensor and tighten the sensor to the tightening specification.






- Use the (VAS 5570) in order to establish the electrical connection between the vehicle and the fuel pressure sensor.






- Connect the vehicle diagnosis tester.

- Turn the ignition on.

- Select "Engine electronics" in OBD.

- Select "Measured values".

- Select "Fuel pressure" from the list.

The current value is displayed in field, which the fuel pressure sensor reports to the Engine Control Module (ECM).

- Turn the (VAS 6394) on by pressing the button - A - briefly.






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

The (VAS 6394/1) should display 0 bar; if this is not the case, then press button - C - one time quickly to set it back to zero.

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






- Start the engine.

- Compare the pressure displayed on the (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, test a new fuel pressure sensor.

Fuel system is under pressure! Fuel pressure must be reduced to a residual pressure before opening high pressure area of the injection system. Refer to => [ Releasing Pressure in High Pressure Area ] Releasing Pressure In High Pressure Area.

- Install a new fuel pressure sensor in the (VAS 6394/1).

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

If the measured values do not now match again:

- Check the electrical connection between the fuel pressure sensor and the ECM.

If the measured values now match:

- Install the new fuel pressure sensor.