Procedures

High Side Fuel Pressure, Releasing

The fuel injection system is separated into a high pressure side, where the pressure is a maximum of approximately 120 bar and a low pressure side, where the pressure is approximately 6 bar.

Before opening the high pressure side, for example, to remove the fuel pressure sensor , the fuel pressure must be reduced to a residual pressure of approximately 6 bar. The procedure for this is as follows:

- Pull the coolant hose secured on the intake manifold to the side and unclip the wiring harness below from its retaining clip.

- Disconnect the fuel pressure regulator valve electrical connector - arrow - from the high pressure pump.






- Allow engine to idle approximately 10 seconds.

• When the fuel pressure regulator valve electrical connector is disconnected during idle, the high side pressure decreases to approximately 6 bar.

• After high side pressure has been decreased, the high pressure side must be opened immediately. Otherwise, the pressure increases again due to the warming of the fuel.

- Turn off the ignition.

The fuel lines are pressurized! Always wear protective eye wear and protective clothing to prevent injuries and fuel from coming in contact with your skin. Before opening the high pressure side, place a cloth around the connection.

- Place a clean cloth around the connection point and carefully open to release the residual pressure of approximately 6 bar. Leaking fuel must be absorbed.

- After completing the work, check the Engine Control Module (ECM) Diagnostic Trouble Code (DTC) memory. Erase all DTC entries which may have been caused by disconnecting the connector.

• If the DTC memory was erased, the readiness code must be generated again. Refer to "Guided Fault Finding" in the vehicle diagnostic tester.