Audi Workshop Service and Repair Manuals

Note:

The activated charcoal filter system solenoid valve 1 is also referred to in this context as fuel tank breather valve.

Testing for leaks

When there is no electrical supply, solenoid valve remains closed.

• ‒ Disconnect hoses from solenoid valve for activated carbon canister (N80).
• ‒ Start final control diagnosis and select solenoid valve for activated carbon canister (N80)
  .

• The valve should click...
• ...and should open and close (check by blowing into the auxiliary hose).

• ‒ If the valve does not click, electrically check the solenoid valve for active carbon canister .
• ‒ If the valve does not open and close correctly, renew solenoid valve 1 for active carbon canister.

Electrical check for solenoid valve 1 for active carbon canister (N80)

• ‒ Unplug connector on ACF valve.
• ‒ → Measure resistance between contacts on valve using hand-held multimeter V.A.G 1526.

• Specified value: 22...30 Ohms

If specified value is not attained:

• ‒ Replace -N80solenoid valve for active carbon canister.

If specified value is attained, check voltage supply => Page 24-138.

Checking solenoid valve voltage supply

Note:

The ACF valve receives its power supply via the fuel pump relay.

Test conditions

• ● Fuse for active carbon canister valve OK

• ‒ Unplug connector on ACF valve.
• ‒ → Connect diode test lamp V.A.G 1527 between engine earth and contact 1 on the connector.
• ‒ Operate starter.

The diode test lamp should light up.

If the diode test lamp does not light up:

• ‒ Check the wiring from contact 1 via the fuse to the fuel pump relay for continuity, repair if necessary.

=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations

• ‒ If wiring is OK, test fuel pump relay => Page 24-57.

If diode test lamp comes on, check activation => Page 24-139.

Testing ACF valve activation

• ‒ → Connect the V.A.G 1527 diode test lamp between contact 2 and contact 1 (positive) in the connector.
• ‒ Start final control diagnosis and select solenoid valve for activated carbon canister (N80)
  . (Please note that final control diagnosis can only be carried out twice if engine was started between tests.)

Diode test lamp should flash.

If the diode test lamp does not flash or is continuously lit:

• ‒ → Connect the V.A.G 1598/31 test box to wiring harness leading to engine control unit; the engine control unit should not be connected
  .

If the diode test lamp is continuously lit:

• ‒ → Test for the line from contact 2 on the ACF valve connector and socket 64 on the test box for a short to earth.

If the diode test lamp does not flash:

• ‒ Check line from contact 2 on active carbon canister valve connector to contact 64 on test box for continuity and for short to positive.

• Wire resistance: max. 1.5 Ohm

• ‒ If necessary, rectify short circuit to earth or open circuit.
• ‒ If no short circuit or open circuit is found, fit a new engine control unit
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