High Side Fuel Pressure, Releasing

High Side Fuel Pressure, Releasing

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 , the fuel pressure must be reduced to a residual pressure of approximately 6 bar. The procedure for this is as follows:

- Move the coolant hose on the intake manifold to the side. Remove the electrical harness underneath, from the clamp.

- Disconnect the fuel pressure regulator valve connector - arrow - from the high pressure pump.






- Allow the engine to idle for approximately 10 seconds.

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

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

- Turn off the ignition.

The fuel lines are under pressure.

Danger of personal injury to eyes and skin.

Wear protective eyewear and protective clothing in order to avoid injury and contact with the skin. Wrap a cloth around the connection before removing a fuel hose. Open the connection carefully and release the pressure.

- 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.

- Check the Engine Control Module (ECM) Diagnostic Trouble Code (DTC) memory. Erase all the faults stored in the DTC memory that may have occurred when the connectors were disconnected.

• If the DTC memory was erased, the readiness code must be generated again. Refer to "Guided Fault Finding" in the vehicle diagnostic tester.