Checking road speed signal: Audi A6 C5 (AFB, AJK, AKE, AKN, …)

🧭 Before you start

Fits: Audi A6 C5 (4B)

• Special tools named: V.A.G 1598/31

Don't miss

• Connect vehicle diagnostic, testing and information systemVAS 5051 A and select vehicle system "“01 - Engine electronics”" from list. Engine must be idling.
• To avoid accident risks when road testing the vehicle with test equipment, always observe the relevant safety precautions . — From the list (1) select diagnostic function "“08 - Read measured value block”".
• 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 .

🔧 Engine codes this applies to

📐 60 workshop diagrams for AFB

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

📋 Procedure

1. Connect vehicle diagnostic, testing and information systemVAS 5051 A and select vehicle system "“01 - Engine electronics”" from list. Engine must be idling.
2. ⚠ To avoid accident risks when road testing the vehicle with test equipment, always observe the relevant safety precautions . — From the list (1) select diagnostic function "“08 - Read measured value block”".
3. Use keypad (2) to enter "“5”" for "“Display group number 005”" and confirm by touching the Q key.
4. Carry out test drive with a 2nd person to observe display zone (3).
5. Terminate diagnosis and switch off ignition.

6. Raise vehicle (if possible using lifting platform) until front left wheel is free to turn.
7. 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 .
8. Connect voltage testerV.A.G 1527 B to sockets "“3”" (positive) and "“54”" (road speed signal) of 121-pin adapter cableV.A.G 1598/31 (test box).
9. Switch on ignition and turn front left wheel by hand.
10. Use current flow diagram to check wiring between adapter cable, 121-pinV.A.G 1598/31 (test box), contact 54 and instrument cluster for open circuit.
11. Repair wiring connection if necessary.

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