High Side Fuel Pressure, Releasing

WARNING: This page is about a different car, the 2008 Volkswagen Jetta, 2008 Volkswagen GLI, 2007 Volkswagen Jetta, and 2006 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.

WARNING:

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

-- Disconnect the electrical connector from the fuel pressure regulator valve -arrow-.

Fig 1: Identifying Fuel Pressure Regulator Valve N276 Electrical Connector

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Allow the engine to idle approximately 10 seconds.

NOTE:

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

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

-- Switch off the ignition.

-- For safety reasons, disconnect the fuel pump control module electrical connector -arrow- before opening the fuel system.

Fig 2: Identifying Fuel Pump (FP) Control Module J538 Connector

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

WARNING:

Fuel lines are pressurized! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before opening the high side, place a cloth around the connection.

-- Place a clean cloth around the connection point and carefully open the high side to release the residual pressure to approximately 6 bar. Leaking fuel must be absorbed.

-- To conclude work, check the Engine Control Module (ECM) Diagnostic Trouble Code (DTC) memory, erase all DTC entries which may have occurred from disconnecting the connector. Refer to ENGINE CONTROL MODULE DTC MEMORY, CHECKING AND ERASING .

NOTE:

If the DTC memory was erased, generate a readiness code. Refer to "Guided Function".