Checking fuel pump relay and actuation: Audi 1.8 (AGU)
Step-by-step checking fuel pump relay and actuation 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
Note:
The fuel pump relay is located in the central electrics in the left hand footwell, relay position 4.
Checking the -J17 fuel pump relay
Remove the storage bin in the front left hand footwell.
Pull fuse 28 out of the fuse holder and connect the V.A.G 1527 diode test lamp between the earth and one of the two contacts for fuse 28.
Operate the starter briefly.
The fuel pump relay should pick up (can be felt and heard) and the diode test lamp should light up.
If the diode test lamp does not light, although the fuel pump relay picks up:
Repeat the test on the other contact on fuse 28.
If the diode test lamp still does not light up:
Check the wiring between contact 23 at relay position 4 and fuse 28 for continuity and, if necessary, rectify open circuit.
=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
If no open circuit is detected, replace the fuel pump relay.
If the fuel pump relay does not pick up:
Check the actuation of the fuel pump relay => Page
24-28
.
Checking the power supply and actuation of the fuel pump relay
Remove the -J17 fuel pump relay from the central electrics, relay position 4.
Checking the power supply
Switch on the ignition.
In sequence, connect the V.A.G 1526 hand held multimeter to contact 19 (positive) and earth and contact 17 (positive) and the earth in the relay panel.
Specified value: approx. battery voltage in each case
If the values are not as specified, rectify the open circuit.
=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
Checking actuation
Connect the V.A.G 1527 diode test lamp to contact 16 (earth) and positive.
The diode test lamp should light up and remain lit when the starter is operated.
Note:
Diode test lamps with a low current consumption do not go out completely but continue to glow faintly until the starter is operated.
If the diode test lamp does not light up, check the wiring as follows:
Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page
24-8
.
Connect the hand-held multimeter between contact 16 on the relay panel and socket 4 on the test box, then check the wiring for an open circuit.
If necessary, rectify open circuit.
=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
If there is no open circuit and the diode test lamp does not light, replace the engine control unit => Page
24-10
.
If the actuation and power supply for the fuel pump relay and the wiring are OK, replace the fuel pump relay.
Replace fuse 28.
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.
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The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.