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 A
• ◆ V.A.G 1598/12
• ◆ VAS 5051 with VAS 5051/1

• or

• ◆ V.A.G 1551 with V.A.G 1551/3 A

Installation position => Installation position overview - Page 24-5

Testing for leaks

ACF solenoid valve -N80 remains closed when de-energised.

• ‒ Disconnect hoses from ACF valve but leave the electrical connector plugged in.
• ‒ Start final control diagnosis and actuate ACF valve.
• ‒ While final control diagnosis is running, blow into solenoid valve to check whether it opens properly. If necessary, replace solenoid valve.

Checking internal resistance

• ‒ Unplug connector on ACF valve.
• ‒ → Connect multimeter between contacts 1 and 2 to measure resistance.
• ‒ Specification: 20 ... 28 ω

If the specification is not obtained:

• ‒ Fit a new ACF valve.

Checking power supply

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 starter briefly.
• ‒ The LED should light up.

If the LED does not light up:

• ‒ Carry out the following tests (marked with dots):

• ● → Check fuse S229 (in fuse holder, position 29).

• ● → Check for open circuit between contact 1 of connector and fuse S229 (in fuse box, position 29).

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

• ● Check fuel pump relay .

Checking actuation

• ‒ → Connect voltage tester V.A.G 1527 B between contacts 1 and 2 using auxiliary cables from V.A.G 1594 A.
• ‒ Start final control diagnosis and actuate ACF solenoid -N80.
• ‒ The LED should flash.

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

• ‒ → With ignition switched off, use adapter V.A.G 1598/12 to connect test box V.A.G 1598 A to connector D only of engine control unit (control unit remains disconnected) => Page 24-9.

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

• ‒ Rectify any open/short circuit as necessary.

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

If no fault is found:

• ‒ Replace engine control unit => Page 24-12.