Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1527 B
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31
• ◆ VAS 5051 with VAS 5051/1

• or

• ◆ V.A.G 1551 with V.A.G 1551/3 A

Note:

In this context, solenoid valve 1 for activated charcoal filter is also designated as fuel tank breather valve, or ACF valve.

Testing for leaks

ACF solenoid valve -N80 remains closed when it is not receiving any current.

• ‒ Disconnect hoses from ACF valve but leave the electrical connector plugged in.
• ‒ Connect an auxiliary hose to one of the connections on the ACF valve.
• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 (or fault reader V.A.G 1551) and select engine electronics control unit by entering address word "01" ( .)
  When doing this the ignition must be switched on.
• ‒ Start final control diagnosis and select solenoid valve for activated charcoal filter -N80 .

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

If valve does not click:

• ‒ Test internal resistance of ACF valve.

If the valve does not open and close properly:

• ‒ Renew activated charcoal filter system solenoid valve -N80.

Testing internal resistance

• ‒ Unplug connector on ACF valve.

• ‒ → Connect multimeter to valve (resistance measurement range)
• ‒ Specification: 22 ... 30 ω

If the specification is not attained:

• ‒ Renew activated charcoal filter system solenoid valve -N80.

If the specification is attained:

• ‒ Test voltage supply => Page 24-108.

Testing voltage supply

Note:

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

Test requirement:

• ● Fuse for ACF valve OK

• ‒ Unplug connector on ACF valve.

• ‒ → Connect voltage tester V.A.G 1527 B as follows:

• ‒ Operate starter briefly.
• ‒ The LED should light up.

If the LED does not light up:

• ‒ Test for open circuit in wiring from contact 1 to fuel pump relay via fuse.

=> Current flow diagrams, Electrical fault finding and Fitting locations

• ‒ Rectify any open circuits.

If the wiring is OK:

• ‒ Test fuel pump relay => Page 24-49.

If the LED lights up:

• ‒ Test activation.

Checking activation

• ‒ → Connect voltage tester V.A.G 1527 B to contact 1 (positive) and contact 2 of the connector.
• ‒ Start final control diagnosis and select solenoid valve for activated charcoal filter -N80 .
• ‒ The LED should flash.

If the LED lamp does not flash or lights up continuously:

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself.
  => Page 24-16.

• ‒ → Test for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify short circuit or open circuit if necessary.

If the wiring is OK:

• ‒ Fit a new engine control unit => Page 24-18.