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 150 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:

- Disconnect the fuel pressure regulator valve (N276) connector - arrow -.






- Allow the engine to idle for approximately 10 seconds.

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

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

- Turn off the ignition.


The fuel system is under pressure!

• Always wear protective eyewear and protective clothing to prevent injuries and fuel from coming in contact with your skin.

• Before loosening line connections, place a cloth around the connection point. Then release pressure by carefully pulling off the line.

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

- Check the Engine Control Module (ECM) Diagnostic Trouble Code (DTC) memory after completing the procedure. Erase all the faults stored in the DTC memory that may have occurred when the connectors were disconnected.

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