SEAT Workshop Service and Repair Manuals

High pressure system pressure reduction. t  The injection system is sub-divided into a high pressure system (max. approx. 120 bar) and a low pressure system (approx. 6 bar). t  Prior to opening the high-pressure component of the injection system, the fuel pressure in the respective circuit must be reduced in a controlled manner to a residual pressure of approx. 6 bar as described in the following. Special tools and workshop equipment required t  Vehicle diagnosis, testing and information system -VAS 505X-

Operation process Proceed as follows: –  With ignition switched off, connect vehicle diagnostic, testing and information system -VAS 505X- with diagnosis lead to diagnosis connection. –  Start engine and run at idling speed.

Indication on -VAS 505X-: –  Select the option vehicle self-diagnosis-Item 1-.

Indication on -VAS 505X-: –  From the menu -1-, select vehicle system „Engine electronics“ and press the → button to continue.

Indication on -VAS 505X-: –  In the option -1-, select the function „measurement values“ and then continue with the → button.

Indication on -VAS 505X-: –  Press keys 140 on keypad -1- to select „Display group 140“ and confirm entry by pressing Q key.

Indication on -VAS 505X-: –  Check display indicating fuel pressure in fuel rail in display zone -3-. l  With engine idling the figure displayed will be approx. 35 bar. The display shows the actual pressure in the fuel rail which is being generated by the high-pressure pump.   WARNING The fuse allocation may have changed depending on the date. You can obtain current information under → Electrical circuit diagrams, fault finding and installation points –  Depending on the model, remove the cover and the respective fuse. On models: Altea, Altea XL, Toledo

–  Remove the cover located under the steering wheel –  Fuse holder under the dash panel - SC47--Fuse 47 in fuse holder C- for the fuel pump control unit -J538-. On model: León

–  Remove the left cover of the dash panel –  Fuse holder on the side of the dash panel - SC27--Fuse 27 in fuse holder C- for the fuel pump control unit -J538-. Indication on -VAS 505X-:

rso –  With engine still running, check display zone -3- for fuel pressure in fuel system: l  The fuel pressure will decrease very quickly because the mechanical high-pressure pump is no longer being supplied with fuel from the fuel tank by the electric fuel pump. –  Switch off ignition as soon as fuel pressure has dropped to just below 8 bar.   Note Fuel pressure must not fall below 6 bar, otherwise the engine will stall (this could damage the catalytic converter). The fuel rail is still full, however, the fuel is no longer under high pressure.   WARNING There is a risk of injury: avoid skin contact with fuel. t  Wear safety goggles and protective clothing when opening the fuel system. t  Before opening the high-pressure section of the fuel system, place a clean cloth around the connection to catch escaping fuel. –  Disconnect a fuel line connection without delay.   Note The pressure will increase again due to the effect of residual heat if the high-pressure system is not opened immediately. Concluding measures –  Insert the fuse in fuse holder C in the respective socket. –  With ignition switched off, connect vehicle diagnostic, testing and information system -VAS 505X-. –  Start „Guided Functions“ mode. –  Generate readiness code in engine control unit → Vehicle diagnostic, testing and information system VAS 5051.