High Side Pressure, Releasing

High Side Pressure, Releasing

CAUTION!
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.

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

- Disconnect the connector from the fuel pressure regulator valve (N276) on the high pressure pump - arrow -.





- Allow the engine to idle approximately 10 seconds.

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

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

- Turn off the ignition.

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

- Place a clean cloth around the connection point and carefully open in order to release the residual pressure to 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.