Checking Lambda probe heater Z19 for Lambda probe G39 — AUDI

🧭 Before you start

Fits: Audi A3 (8L, 1996–2003)

• Special tools named: V.A.G 1598/31
• Renewed: engine control unit

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• The point at which the engine control unit switches the Lambda probe heating on and off can be observed if applicable in the "“Reading measured value block”" function, display group number 041, display zone 2.
• 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 .

🔧 Engine codes this applies to

📋 Procedure

1. Unscrew the protective cover (arrows).
2. Unplug the 6-pin connector (black) to the Lambda probe G39.
3. Connect up the multimeter (resistance measuring range) between contacts 3 and 4.
4. Replace the Lambda probe G39.
5. Check voltage supply for Lambda probe heating.

6. Connect up the multimeter (voltage measuring range) between contacts 3 and 4.
7. Start engine. [Note: The point at which the engine control unit switches the Lambda probe heating on and off can be observed if applicable in the "“Reading measured value block”" function, display group number 041, display zone 2.]
8. Connect up the multimeter (voltage measuring range) as follows.
9. Briefly operate the starter.
10. Check for open circuit in the wiring from contact 3 of the connector via the fuse to the fuel pump relay:
11. Connect up the multimeter (voltage measuring range) as follows:
12. Start engine. [Note: The point at which the engine control unit switches the Lambda probe heating on and off can be observed if applicable in the "“Reading measured value block”" function, display group number 041, display zone 2.]
13. Switch off ignition.
14. 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 .
15. Check for open circuit in the following wiring:
16. Eliminate open circuit in wiring if necessary.
17. Replace the engine control unit .

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