Procedures

Releasing Pressure on High Pressure Side

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 high pressure side - e.g. removing high pressure pump, fuel rail, fuel injectors, fuel pipes or fuel pressure sensor (G247) - fuel pressure in high pressure side must be reduced to a residual pressure of approximately 6 bar. The procedure for this is as follows.

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





- Allow engine to idle approximately 10 seconds.

• When the fuel pressure regulator valve (N276) electrical connector is disconnected during idle, the pressure in the high pressure side decreases to approximately 6 bar.

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

- Switch off ignition.

CAUTION!
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 to release the residual pressure of approximately 6 bar. dripping fuel must be absorbed.

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

• If DTC memory was erased, generate readiness code.