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Audi, A6, C4, 2.6 Quattro (1994-) Common Issues

1. Faulty Rear Axle Bearing

Occurrence: 15%Cost to repair: $1200

Symptoms:

Rumbling or growling noise from rear axle, vibrations when driving


2. Catalytic Converter Failure

Occurrence: 20%Cost to repair: $1000

Symptoms:

Rough idling, decreased power, strong smell of gasoline near catalytic converter


3. Faulty Oxygen Sensor

Occurrence: 18%Cost to repair: $450

Symptoms:

Poor engine performance, rough idling, decrease in fuel efficiency


4. Transmission Problems (Tiptronic)

Occurrence: 12%Cost to repair: $850

Symptoms:

Unusual noises or hesitation when shifting gears, inability to shift into certain gear modes


5. Faulty Alternator

Occurrence: 14%Cost to repair: $650

Symptoms:

Dimming headlights, electrical system failures (radio, wipers, etc.), slow engine crank


6. Rust Issues with Rear Wheels

Occurrence: 16%Cost to repair: $300

Symptoms:

Corrosion visible on rear wheel wells and surrounding areas


7. Faulty ECU (Engine Control Unit)

Occurrence: 9%Cost to repair: $950

Symptoms:

Poor engine performance, random error messages on dashboard, inability to start engine


8. Water Pump Failure

Occurrence: 11%Cost to repair: $900

Symptoms:

Coolant leaks near water pump, overheating engine, hissing sounds