Testing and adjusting idling switch: Audi 4.2 (AHK)
Step-by-step testing and adjusting idling switch for the Audi 4.2 (AHK): factory workshop text. What to remove, in what order, and what to check after.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
🔧 Engine codes this applies to
📋 Procedure
The idling switch is located at the rear of the throttle valve body in the throttle valve potentiometer.
Connect fault reader V.A.G 1551 (V.A.G 1552) and select control unit for engine electronics => Page
01-2
.
Read measured value block (function 08) and select display group 04 =>Page
01-90
).
Read measured value block 4
⇒
1
2
3
4
Readout on display:
Check display in display zone 4.
Specification: "Idling"
If "part throttle" does not appear until after considerable pedal travel, adjust the idling switch.
Depress the accelerator pedal very slightly (only a few millimetres).
Specification: "Part throttle"
If the readout does not change as described, check the setting of the accelerator cable.
=> 8-cylinder engine, Mechanical components; Repair Group 20; Servicing throttle control; Adjusting throttle cable
8-cylinder engine, Mechanical components
Servicing throttle control
Adjusting throttle cable
If the setting of the throttle cable is OK, test the idling switch and the wiring connections.
Adjusting idling switch
The throttle valve body needs to be removed in order to adjust the idling switch.
Note:
Adjusting the idling switch also automatically adjusts the throttle valve potentiometer.
Slacken both bolts of the throttle valve potentiometer.
Turn throttle valve potentiometer in direction of arrow until a stop is felt. The throttle valve (throttle mechanism) must not be moved during this step.
Tighten throttle valve potentiometer in this position.
Testing wiring connections
Connect test box V.A.G 1598/19 to wiring harness for engine control unit =>Page
24-14
.
Unplug the connector from the throttle valve potentiometer.
Test the following wires for continuity and short circuits:
Connector on wiring harness, contact · Test box V.A.G 1598/19 or engine control unit
4 · D11
6 · B4
Rectify any open/short circuit as necessary.
=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
Note:
Only use gold-plated contacts when repairing the contacts in the throttle valve positioner connector.
If the wiring is OK, replace the throttle valve potentiometer.
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
Ask about my car →Other AUDI procedures
- Fitting locations overview
- Replacing engine control unit
- Testing air mass meter
- Servicing valve gear
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.