Checking the injectors: Audi 1.8 (AGU)
Step-by-step checking the injectors for the Audi 1.8 (AGU): 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
Electrical checks on injectors
Remove the plug connector from the injector which is to be tested.
Measure the resistance between the injector contacts using the V.A.G 1526 hand held multimeter.
Specified value: 13...18 ω.
If the engine is warm, the resistance will be approx. 4...6 ω.
If the measured value is not as specified, replace the injector.
Checking the power supply to the injectors
Test conditions
Fuse for injectors OK.
Remove the plug connector from the injector which is to be tested.
Connect the V.A.G 1527 diode test lamp between contact 1 and the engine earth.
Operate the starter for a few seconds (the engine can be allowed to start).
The diode test lamp should light up.
If the diode test lamp lights up, test the actuation of the injectors.
If the diode test lamp does not light up:
Check the wiring from contact 1 via the injector fuse to the fuel pump relay for continuity and, if necessary. rectify open circuit.
=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
Checking injector actuation
Remove the plug connector from the injector which is to be tested.
Connect the V.A.G 1527 diode test lamp between contact 2 and the battery's positive terminal.
Operate the starter briefly (the engine may start briefly).
The diode test lamp should flash.
Note:
Diode test lamps with a low current consumption do not go out completely between the flashing pulses, but continue to glow slightly and become much brighter during the flashing pulses.
If the diode test lamp does not flash:
Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page
24-8
.
Check the wiring between contact 2 on the connector for the injector in question and the engine control unit for continuity or a short to positive.
Contact 2 on plug the connector for injector · Test box V.A.G 1598/22 Contact
1 · 73
2 · 80
3 · 58
4 · 65
If necessary, rectify open circuit or short circuit.
If the wiring is OK, replace the engine control unit => Page
24-10
.
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.