Fuel Pressure Release: Service and Repair

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 lines or Fuel Pressure Sensor G247 - fuel pressure in high pressure area must be reduced to a residual pressure of approx. 6 bar. The procedure for this is as follows.

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







- Remove connector from Fuel Pressure Regulator Valve N276 on high pressure pump -arrow -.
- Allow engine to idle approx. 10 seconds.

NOTE:
- When the Fuel Pressure Regulator Valve N276 electrical connector is disconnected during idle, pressure in high pressure area decreases 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), erase all DTC entries which may have occurred from removing the connector.

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