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

Testing for leaks

ACF solenoid valve -N80 remains closed when deenergised.

• ‒ Disconnect hoses from ACF valve but leave the electrical connector plugged in.
• ‒ Connect auxiliary hose to one connection of ACF valve.
• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 -Engine electronics" in the selection. For this purpose, the engine must be running at idling speed.
• ‒ Initiate final control diagnosis and actuate ACF solenoid valve -N80 .

→ Display on VAS 5051:

•     A -    1st control element in test
•     1 -     Fuel tank breather valve -N80

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

If the injector does not click:

• ‒ Checking internal resistance to ACF valve.

If valve does not open or close properly:

• ‒ Replace -N80 solenoid valve for activated charcoal filter.

Checking internal resistance

• ‒ Unplug connector on ACF valve.

• ‒ → Connect multimeter between contacts 1 and 2 on valve to measure resistance.
• ‒ Specified value: 22 ... 30 ω

If specification is not attained:

• ‒ Replace -N80 solenoid valve for activated charcoal filter.

If specified value is attained:

• ‒ Check the voltage supply
  .

Checking power supply

Test requirements:

• ● Fuse for ACF valve OK.

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

• ● Fuel pump relay OK; checking .

Note:

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

• ‒ Unplug connector on ACF valve.

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

• ‒ Operate the starter briefly (the engine may start).
• ‒ The LED should illuminate.

If the LED does not illuminate:

• ‒ Check the wiring from contact 1 on the connector via the fuse to the fuel pump relay for an open circuit:

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

• ‒ Rectify open circuit, if necessary.

If the LED illuminates:

• ‒ Check actuation.

Checking actuation

• ‒ → Connect voltage tester V.A.G 1527 B to contacts 1 (positive) and 2 of the connector.
• ‒ Initiate final control diagnosis and actuate ACF solenoid valve -N80 .
• ‒ The LED should flash.

If the LED lamp does not flash or if it illuminates continuously:

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page 24-19.

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

• ‒ Rectify any open/short circuit as necessary.

If the wiring is OK:

• ‒ Replace engine control unit => Page 24-32.