SEAT Workshop Service and Repair Manuals

Procedure before opening the high pressure injection system. Warning! The injection system is sub-divided into a high pressure system (max. approx. 110 bar) and a low pressure system (approx. 6 bar). Prior to opening the high-pressure section, e.g. before removing the high-pressure pump, fuel rail, injectors, intake manifold flap motor for air-flow control or any other component located in the high-pressure zone of the injection system, the fuel pressure in the high-pressure section must be reduced to a residual pressure of approx. 8 bar. The procedure is described below. Special tools and workshop equipment required

t  Diagnosis centre -VAS 5051-

t  Cable 3m. -VAS 5051/5A- or cable 5m. -VAS 5051/6A-

Procedure –  Remove the connector to the activated charcoal filter system solenoid valve 1 (pulsed) -N80--1- –  Start the engine and run at idling speed.   Note next, select the control unit with the VAS 5051, then select display group 140 under the function „Read measured value block“.

–  Connect the central diagnosis -VAS 5051- with the 3m. cable -VAS 5051/5A- or 5m. cable -VAS 5051/6A-. –  Briefly press the key „Vehicle self diagnosis“.

Indication on - VAS 5051 -: –  Select vehicle system „01 - Engine electronics“ in menu -1-. –  Wait until the following is displayed.

Indication on - VAS 5051 -: –  Select diagnosis function „08 - Read measured value block“ in menu -1-.

Indication on - VAS 5051 -: –  Key in display group 140 on keyboard -2- and confirm entry by briefly pressing key Q.

Indication on - VAS 5051 -: 1 -  Display field 1 2 -  Display field 2 (specified pressure) 3 -  Display field 3 (real pressure) 4 -  Display field 4 5 -  Display group X Observe the display in display field 3. The value of the idle run shown in display field 3 is approx. 39 bar. The display shows the effective pressure (true pressure) in the fuel rail (common channel) generated by the high pressure pump. Display field 2 shows the pre-established pressure (specified pressure) The specified value should be the same as the true value.

–  Remove fuses -4- and -43-(for the electric fuel pump control unit) in the fuse holder, below the instrument panel, left-hand side, and continue reading display field 3. The engine continues to run at idling speed. The value shown in display field 3 drops rapidly as the mechanical high pressure pump is no longer fed by the electric fuel pump from the tank.   Note The display should not read below 6 bar; if so, the engine will stall (with the ensuing risk that the catalytic converter is damaged). –  Switch off the ignition when the value displayed reaches approx. 8 bar. The fuel rail is still full, however, the fuel is no longer under high pressure. The components or pipes may now be disconnected. Put a clean cloth around the joints. Catch the fuel coming out. –  Reinsert fuses 4 and 43 (for the fuel pump control unit).

–  Attach the connector from the activated charcoal filter system solenoid valve 1 (pulsed) -N80--1- –  When the repair is finished, consult the fault memory of the engine control unit and erase it → Chapter.