Procedures

High Side Pressure, Reducing

Special tools, testers and auxiliary items required

• Assembly Tool (T10118)


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 (G247), the fuel pressure must be reduced to a residual pressure of approximately 6 bar. The procedure for this is as follows:.

- Disconnect the electrical connector - 1 - from the fuel pressure regulator valve (N276) using assembly tool (T10118).





- Allow the 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 the high side pressure has been released, the high pressure side must be opened, otherwise the pressure increases again due to the warming of the fuel.

- Turn off the ignition.


The fuel lines are pressurized! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before opening the high side pressure, place a cloth around the connection.

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

- To complete the procedure, check the Engine Control Module (ECM) Diagnostic Trouble Code (DTC) memory and erase all DTC entries which may have been caused by removing 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.