Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1998 Audi A4 AvantFACTORY OEM SERVICE PROCEDURE
Mil Check: Cabriolet
- Turn ignition on. MIL should light. If MIL lights, go to step 3). If MIL does not light, go to next step.
- MIL is not lighting due to faulty wiring or an open circuit. Turn ignition off. Inspect MIL bulb. If bulb is okay, check wiring between MIL and PCM. PCM is located in floor cavity under passenger side carpeting. See WIRING DIAGRAMS article. If wiring is okay, replace faulty PCM. See PCM REPLACING .
- Start engine and let it idle. MIL should go out after a few seconds. If MIL goes out, MIL is functioning properly. If MIL does not go out, check for any stored DTCs. See RETRIEVING CODES under SELF-DIAGNOSTIC SYSTEM. If DTCs are stored, repair as necessary. If no DTCs are stored, go to next step.
- MIL is on continuously due to a short to ground. Turn ignition off. Check for a short circuit between MIL and Powertrain Control Module (PCM). See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace faulty PCM. See PCM REPLACING .
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.