1994 Audi 90 CS QuattroFACTORY OEM SERVICE PROCEDURE

Control Module Does Not Answer

Press HELP button to generate a list of possible malfunction causes. Check DLC wiring. See CHECKING DLC WIRING. Check for defective ECM by performing diagnostic procedure for Code 65535. After eliminating cause, enter address word "01" to select ENGINE ELECTRONICS.

Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.