Procedures

High Side Fuel Pressure, Releasing

CAUTION!
The fuel injection system is divided into a high pressure side (maximum approximately 120 bar) and a low pressure side (approximately 6 bar).

Before opening the high pressure side, for example, removing the high pressure fuel pump, fuel rail, fuel injectors, fuel pipes or fuel pressure sensor (G247). The high side fuel pressure must be reduced to a residual pressure of approximately 6 bar. The procedure for this is as follows:

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





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

- Turn off the ignition.

CAUTION!
The fuel system is under pressure!

• Wear protective goggles and protective clothing to prevent injuries and contact with skin.

• Before disconnecting the connection, place a cloth around the connection point. Then release pressure by carefully disconnecting 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.

- To conclude work, check the Diagnostic Trouble Code (DTC) memory of the Engine Control Module (ECM), erase all DTC entries which may have occurred from disconnecting the connector.

• If the DTC memory was erased, generate a readiness code. Refer to "Guided Function" in the vehicle diagnostic tester.