Checking lambda probe heater Z19 for lambda probe upstream of catalytic converter — AUDI

🧭 Before you start

Fits: Audi TT Mk1 (8N)

• Renewed: engine control unit removing

Don't miss

• The point at which the engine control unit switches the lambda probe heating on and off can be observed in display zone 2 of "“measured value block 041”".
• Connect 121-pin adapter cableV.A.G 1598/31 (test box) to wiring harness to engine control unit, but do not connect actual engine control unit .

🔧 Engine codes this applies to

📐 54 workshop diagrams for BAM

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

📋 Procedure

1. Unplug 6-pin connector (black) to lambda probe G39 (upstream of catalytic converter).
2. Connect up multimeter (resistance measuring range) between contacts (3) and (4).
3. Replace lambda probe upstream of catalytic converter.
4. Check power supply of lambda probe heating.
5. Connect up multimeter (voltage measuring range) between contacts (3) and (4).

6. Start engine. [Note: The point at which the engine control unit switches the lambda probe heating on and off can be observed in display zone 2 of "“measured value block 041”".]
7. Connect up multimeter (voltage measuring range) between contact (3) (positive) and earth.
8. Briefly operate starter.
9. Use current flow diagram to check wiring from contact (3) of connector via fuse to fuel pump relay for open circuit.
10. Connect up multimeter (voltage measuring range) between contact (4) (engine control unit switched earth connection) and battery positive.
11. Start engine. [Note: The point at which the engine control unit switches the lambda probe heating on and off can be observed in display zone 2 of "“measured value block 041”".]
12. Switch off ignition.
13. Connect 121-pin adapter cableV.A.G 1598/31 (test box) to wiring harness to engine control unit, but do not connect actual engine control unit .
14. Check for open circuit in the following wiring:
15. Repair wiring if necessary.
16. Replace engine control unit Removing and installing engine control unit without protective housing or Removing and installing engine control unit with protective housing.

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