Releasing Pressure In High Pressure Area
The fuel injection system is separated into a high-pressure section where the pressure is a maximum of approximately 120 bar (1740 psi) and a low-pressure section where the pressure is approximately 6 bar (87 psi).
Before opening the high pressure area, for example to remove the fuel pressure sensor -G247-, the fuel pressure must be reduced to a residual pressure of approximately 6 bar (87 psi). The procedure for this is as follows.
-- Move the coolant hose on the intake manifold to the side. Remove the electric wiring harness underneath from the clamp.
-- Disconnect the connector from the fuel pressure regulator valve -N276- on the high pressure pump -arrow-.
-- Let the engine run at idle for approximately 10 seconds.
When the fuel pressure regulator valve -N276- electrical connector is disconnected during idle, pressure in the high pressure area decreases to approximately 6 bar (87 psi).
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.
-- Turn off the ignition.
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 fuel hoses. 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 (87 psi). Escaping 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 → vehicle diagnostic tester in "Guided Fault Finding".