Technician Safety Information

Pressure release in high pressure area

CAUTION! The fuel injection system is divided into a high pressure section (maximum approx. 120 bar) and a low pressure system (approx. 6 bar).
Before opening high pressure area, e.g. removing high pressure pump, fuel rail, fuel injectors, fuel line or Fuel Metering Valve N290 or Fuel Metering Valve 2 N402, fuel pressure in high pressure area must be reduced to a residual pressure of 6 bar. The procedure for this is as follows.





- Disconnect connector from Fuel Metering Valve N290 on right high pressure pump -arrow-.





- Disconnect connector from Fuel Metering Valve 2 N402 on left high pressure pump -arrow-.

- Allow engine to idle approx. 10 seconds.

Note: If the fuel metering valve electrical connectors are disconnected in idle, the pressure in the high pressure area drops to approx. 6 bar.
After high pressure has been released, high pressure system 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 system, place a cloth around the connection.

- Place a clean cloth around connection point and carefully open to release residual pressure of approx. 6 bar. Escaping fuel must be absorbed.
- To conclude work, check DTC memory of Engine Control Module (ECM) J623, erase all DTC entries which may have occurred from removing connector.

Note: If DTC memory was erased, generate readiness code "Guided Function".