Testing engine speed signal — AUDI
Testing engine speed signal on Audi: factory workshop procedure for engines 1Z, AEB, AFF, AFN. Full factory text, tools and checks.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📋 Procedure
AHU AFN 1Z
The engine speed signal is required for rev counter, air conditioner and automatic gearbox.
The signal shape generated by the engine speed sender -G28 cannot however be evaluated and is therefore conditioned beforehand in the engine control unit.
Establish engine speed signal as follows:
Dash panel insert
Observe reading on rev counter.
The current engine speed must be displayed.
Air conditioner
Connect fault reader V.A.G 1551
=> Page
Rapid data transfer
HELP
Enter address word
XX
Display:
Rapid data transfer
Q
08 - Air conditioner
Enter 08 for address word "Air conditioner" and acknowledge with Q.
Press ⇒ -button.
Rapid data transfer
HELP
Select function
XX
Display:
Enter 08 for function "Read measured value block" and acknowledge with Q.
Read measured value block
HELP
Enter display group number XX
Display:
Enter 09 for display group "09" and acknowledge with Q.
Read measured value block 9
⇒
1
2
3
4
Display:
Observe reading in display field 1.
The current engine speed must be displayed.
Automatic gearbox
Connect fault reader V.A.G 1551
=> Page
Rapid data transfer
HELP
Enter address word
XX
Display:
Rapid data transfer
Q
02 - Gearbox electronics
Enter 02 for address word "Gearbox electronics" and acknowledge with Q.
Press ⇒ -button.
Rapid data transfer
HELP
Select function
XX
Display:
Enter 08 for function "Read measured value block" and acknowledge with Q.
Read measured value block
HELP
Enter display group number XX
Display:
Enter 03 for display group "03" and acknowledge with Q.
Read measured value block 3
⇒
1
2
3
4
Display:
Observe reading in display field 2.
The current engine speed must be displayed.
If desired value is not attained for all "receivers" of engine speed signal, this may be due to the following:
Cable break/short circuit between control unit for diesel direct injection system, contact 2 and distributor in instrument panel wiring loom.
=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations binder
Short circuit between distributor in instrument panel wiring loom and "receiver".
Diesel direct injection system control unit defective
If desired value is attained with at least one "receiver" of engine speed signal, this may be due to the following:
Cable break between distributor in instrument panel wiring loom and "receiver".
"Receiver" defective.
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.
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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.