Testing fuel pump relay — AUDI
Testing fuel pump relay on Audi: factory workshop procedure for engines AEB, AGA, AJG, AJL. Full factory text, tools and checks.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📐 46 workshop diagrams for AEB
Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.
📋 Procedure
AJG ALF
The fuel pump and some of the injection system components are powered via the fuel pump relay -J17.
The fuel pump relay -J17 will only close if the engine is turning over. In other words, the relay is only earthed (via the engine control unit) when the engine control unit is receiving engine speed impulses.
Test conditions
Battery voltage at least 11 V
Functional test of fuel pump relay
Start final control diagnosis and activate one of the injectors
=> Page
01-26
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Final control diagnosis
⇒
Injector, Cylinder 1 -N30
Indicated on display:
The fuel pump relay (central electrics, relay position 4) should pick up...
If the relay does not pick up, test activation of fuel pump relay
=>Page
24-45
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...and the fuel pump should run.
If the fuel pump does not run, test activation of fuel pump and components =>Page
24-47
.
Testing activation of fuel pump relay
Switch off ignition.
Connect test box V.A.G 1598/22 to wiring harness for engine control unit
=> Page
24-21
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Connect sockets 2 and 4 of test box to each other using auxiliary cable from V.A.G 1594.
Switch ignition on.
Specification: The fuel pump relay (central electrics, relay position 4) should pick up.
If the relay picks up now but not during the final control diagnosis:
Fit a new engine control unit.
If the relay does not pick up:
Switch off ignition.
Disconnect fuel pump relay from relay panel (central electrics, relay position 4).
Connect hand-held multimeter (voltage measurement range) between earth and contact 19 on relay panel.
Switch ignition on.
Specification: approx. battery voltage
If the specification is not attained:
Check the wiring.
=> Current flow diagrams, Electrical fault finding and Fitting locations binder
If the specification is attained:
Switch off ignition.
The following wiring connections are to be checked for open circuits and/or short to positive or negative.
Contact No., relay position 4, central electrics · Socket on test box V.A.G 1598/22
16 · 4
Rectify any open/short circuit as necessary.
If the fuel pump relay activation, voltage supply and wiring are OK, fit a new fuel pump relay.
Testing activation of fuel pump and components
Remove fuses 28, 29 and 34.
Start final control diagnosis and activate one of the injectors
=> Page
01-26
.
Connect hand-held multimeter (voltage measurement range) between earth and the left-hand or right-hand contact of the following fuses:
Fuse No. · Specification for left-hand or right-hand contact
28 · approx. battery voltage
29 · approx. battery voltage
34 · approx. battery voltage
If the specification is not attained:
Check wiring
=> Current flow diagrams, Electrical fault finding and Fitting locations binder
If no fault in wire is detected:
Fit a new fuel pump relay -J17.
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.