Checking Motronic current supply relay J271: Audi A3 1.8 (ARX, ARY, AUM, AUQ, …)

🧭 Before you start

Engine cover off, 4-pin connector unplugged at an ignition coil, multimeter on the voltage range: readings are taken with the ignition on, then off. The relay is detached from beneath the cover at the left of the bulkhead, its voltage supply is measured and the connections traced on the current flow diagram, with any open circuit repaired. The checks marked with a dot are worked through, then the test box is connected to the engine control unit harness (control unit disconnected) to check for open circuit and short to earth or positive. If the wiring is sound, the relay is renewed.

Fits: Audi A3 (8L, 1996–2003)

• Special tools named: V.A.G 1598/31

Don't miss

• Switch the ignition off before detaching the relay or connecting the test box.
• Connect the test box to the harness only, never with the engine control unit plugged in.
• Repair any open circuit or short in the wiring before condemning the relay.
• Renew J271 only after the supply and wiring checks pass.
• Work from the current flow diagram with the multimeter on the voltage range, not by guesswork.

Written for this job from the workshop steps below · TorqFix editorial.

🔧 Engine codes this applies to

📐 43 workshop diagrams for ARX

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

📋 Procedure

1. Remove the engine cover (arrows).
2. Unplug the 4-pin connector (1) at one of the ignition coils (2).
3. Connect up the multimeter (voltage measuring range) as follows.
4. Switch on ignition.
5. Switch off ignition.

6. Detach the current supply relay (1) beneath the cover on the left at the bulkhead.
7. Use the current flow diagram to check for open circuit in the following connection:
8. Eliminate open circuit in wiring if necessary.
9. Check voltage supply of Motronic current supply relay J271.
10. Switch off ignition.
11. Detach the current supply relay (1) beneath the cover on the left at the bulkhead.
12. Connect up the multimeter (voltage measuring range) as follows.
13. Perform the following checks marked with a dot:
14. Switch off ignition.
15. Detach the current supply relay (1) beneath the cover on the left at the bulkhead.
16. Connect up the multimeter (voltage measuring range) as follows.
17. Switch on ignition.
18. Switch off ignition.
19. Connect the test box V.A.G 1598/31 to the wiring harness to the engine control unit, but do not connect the actual engine control unit .
20. Check for open circuit and short to earth or positive in the following wiring:
21. Eliminate open circuit in wiring/short circuit if necessary.
22. Renew Motronic current supply relay J271.

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