Audi , A6 , C5 , 1.8 5v (1997-) Common Issues

Most Common Issues:

1. Faulty Oxygen Sensor (20-30% failure rate)
2. Intermittent Spark Plug Wire Failure (15-25%)
3. Leaking Coolant System (10-20%)
4. Faulty Mass Airflow Sensor (5-15%)
5. Worn or Loose Timing Chain Tensioner (5-15%)

Moderately Common Issues:

1. Ignition Coil Failures (5-12%)
2. Cracked Cylinder Head Gasket (3-10%)
3. Leaking Oil Seals on the Crankshaft Pulley (2-8%)
4. Faulty PCV Valve (2-6%)
5. Worn or Loose Spark Plug Wire Boots (2-5%)

Less Common Issues:

1. Faulty Fuel Pressure Regulator (1-4%)
2. Intermittent Transmission Problems (1-3%)
3. Leaking Water Pump Seal (1-3%)
4. Faulty Throttle Position Sensor (0.5-2%)
5. Worn or Loose Rear Main Seal (0.5-2%)

Rare Issues:

1. Engine Block Cracking (less than 0.5%)
2. Head Gasket Failure (less than 0.5%)
3. Crankshaft Failure (less than 0.5%)
4. Piston Ring Seizure (less than 0.5%)
5. Main Bearing Failure (less than 0.5%)