Procedures

High Side Fuel Pressure, Releasing

Special tools, testers and auxiliary items required

• Assembly Tool (T10118)

Procedure

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 pump, fuel rail, fuel injectors , fuel pipes or fuel pressure sensor, 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 fuel pressure regulator valve connector - 1 - using the assembly tool (T10118).






- Allow the engine to idle approximately 10 seconds.

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

• After the high side pressure has been released, the high 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!

• For safety reasons, interrupt the current supply to the fuel pump, refer to => [ Ignition System ] Ignition System before opening the fuel system because the fuel pump is activated by the drivers door contact switch.

• Always wear protective eyewear 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.

• By disconnecting the connectors, Diagnostic Trouble Codes (DTCs) are stored to memory. After assembling, check the fault memory and erase, if necessary.

- Check the Engine Control Module (ECM) DTC memory and erase any entries using "Guided Functions" in the vehicle diagnostic tester.

• Generate a readiness code if the DTC memory was erased. Refer to "Guided Functions" in the vehicle diagnostic tester.