Checking activated charcoal filter system control: VW 2.5 (AAF, ACU, AET, API, …)

ACU AET API AVT
Vehicles ▸ 04.99

Vehicles 05.99 ▸ => Page
20-34

Test conditions

Lambda probe and Lambda control OK, checking
=>Repair group 24.
Engine oil temperature at least 80°C.

Test sequence

Pull off hose (from activated charcoal filter) at solenoid valve (N80) -arrow-.
Start the engine and run at idling speed.

Vehicles ▸ 02.94

The valve must not operate (pulse) and the vacuum at valve connection is not perceptible.

Continued for all vehicles

Increase engine speed.
The valve must operate periodically (pulse)
-vacuum perceptible at connection-.

Valve does not operate (pulse):

Vehicles with final control diagnosis 10.91 ▸

=> Repair group 01; Self-diagnosis, final control diagnosis
5-cyl. fuel injection engine, Mechanics
Self-diagnosis, final control diagnosis

Vehicles without final control diagnosis ▸09.91

=> Repair group 01; Electrical check; wiring and component check with test box V.A.G 1598
5-cyl. fuel injection engine, Mechanics
Electrical check
wiring and component check with test box V.A.G 1598

Switch off ignition.
Pull connector off solenoid valve and connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 to connector.
Start engine and increase speed.
LED must flicker briefly.

If LED does not flicker:

Locate and eliminate wiring open circuit to engine control unit according to current flow diagram or renew control unit.

If the voltage supply is OK.:

Renew activated charcoal filter system solenoid valve (N80).

Vehicles 05.99 ▸

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
Test box V.A.G 1598/31
Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
Adapter set V.A.G 1594
Current flow diagram

Check conditions

Coolant temperature must be at least 80 °C, =>display group 04, display zone 3.

Functional check

Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select engine electronics control unit with the "Address word" 01.

=> Repair group 01; Self-diagnosis; connecting fault reader V.A.G 1551 and selecting engine control unit.
5-cyl. fuel injection engine, Mechanics
Self-diagnosis
connecting fault reader V.A.G 1551 and selecting engine control unit.

Rapid data transfer
HELP
Select function XXX
Indicated on display:

Rapid data transfer
HELP
Select function XXX
Indicated on display:

Press keys 0 and 4 for the "Introduce basic setting" function and confirm entry with Q key.

Basic setting
Input display group number XXX
Indicated on display:

Press keys 0, 7 and 0 for "Display group number 70" and confirm entry with Q key.

System in basic setting
70
⇒
1
2
3
4
Indicated on display:
(1...4 = Display zones)

When the diagnosis is initiated by the engine control unit the display in display zone 4 jumps from "Test OFF" to "Test ON"

Run engine at idling speed until the
specification "TVV OK"
is displayed in display zone 4.

If the display does not indicate as described:

Interrogate fault memory

=> Repair group 01; Self-diagnosis; Interrogating and erasing fault memory
5-cyl. fuel injection engine, Mechanics
Self-diagnosis
Interrogating and erasing fault memory

Perform final control diagnosis

=> Repair group 01; Self-diagnosis, final control diagnosis
5-cyl. fuel injection engine, Mechanics
Self-diagnosis, final control diagnosis