Checking knock sensors: Audi TT Mk1 (AJK, ARE, ARX, ARY, …)

🧭 Before you start

Unplug the knock sensor connector and check for shorts between contacts (1 + 2), (1 + 3) and (2 + 3); renew the sensor if any are shorted. Connect the 121-pin test box V.A.G 1598/31 to the engine harness without the control unit and check the wiring for open circuit and shorts to positive or earth, repairing as needed. Finally remove the sensor and measure resistance between contacts (1) and (2).

Fits: Audi TT Mk1 (8N)

• Special tools named: V.A.G 1598/31
• Renewed: knock sensor

Don't miss

• Do not connect the engine control unit to the test box while checking the wiring.
• Check all three contact pairs for shorts before condemning the wiring.
• Identify which sensor you are testing: G61 is item 1, G66 is item 2.
• A knock sensor must sit clean and flat on its boss; general practice is to clean the mounting face before refitting.

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

🔧 Engine codes this applies to

📋 Procedure

1. Unplug connector of knock sensor 1G61(item 1) or knock sensor 2G66(item 2) in engine compartment.
2. Check for short circuits between the wires. Consecutively connect multimeter (voltage measurement range) to contacts (1 + 2), (1 + 3) and (2 + 3).
3. If there is a short circuit between the contacts, fit a new knock sensor.
4. Check the wiring.
5. Connect adapter cable, 121-pin V.A.G 1598/31 (test box) to wiring harness for engine control unit, but do not connect the engine control unit itself .

6. Check for open circuit and short to positive or earth in the following wiring:
7. Repair wiring connection if necessary.
8. Remove knock sensor.
9. Unplug electrical connector.
10. Connect multimeter (resistance measurement range) between contacts (1) and (2) on knock sensor.
11. Renew knock sensor.
12. Connect adapter cable, 121-pin V.A.G 1598/31 (test box) to wiring harness for engine control unit, but do not connect the engine control unit itself .
13. Check for open circuit and short to positive or earth in the following wiring:
14. Repair wiring connection if necessary.

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