2004 Audi A6 Quattro Repair and Maintenance

A guide to problems, costs, maintenance and repair for your 2004 Audi A6 Quattro

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2004 Audi A6 Quattro Problems

No Start after Refueling and Popping Noise from Trunk

Popping sounds from the rear of the vehicle may be heard moments after starting the engine, or when slowing to a stop. This noise is from the leak detection pump filling the fuel tank with air, and releasing to retest the system when it finds a fault. The sequence of faults identifying this issue are as follows:

  • Succession of loud pops from rear of vehicle
  • Pops go away, and fuel economy decreases 
  • Check engine light illuminates
  • OBD trouble code P2404 and/or P0441 is stored
  • Engine will not start after refueling (must crank for over 30 seconds)
  • Vibration when slowing to a stop

The cause is a valve which is mounted on the front of the intake manifold, commonly called the N80 valve, or EVAP system purge valve. The valve is designed to open under specific circumstances, but a worn valve will remain open at all times, preventing the pressurization of the fuel tank. 

Correction of the issue is to replace the N80 valve with the latest revision. 

Check Engine Light and/or Engine Overheating Due to Failed Thermostat

The thermostat may erratically stick open or closed. The can result in illumination of the Check Engine Light and/or engine overheating.

ABS Light Due to Control Module Failure

The anti-lock brake system (ABS) control module may fail causing the ABS light to illuminate. Failed modules should be replaced to restore ABS operation.

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2004 Audi A6 Quattro Questions

ESP light on (1 answer)

comes on while driving

EPS light on (1 answer)

EPS light comes on while driving. usually when i come to a stop

My car blew a water hose and automatically shut down. now it won't start. (1 answer)

While driving the low oil light came on. And then the hose blew. The car shut down and after filling it with oil and repairing the hose, now the car won't start. Not even turn over. The EPC light is on as well.

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2004 Audi A6 Quattro Reviews

Rated
based on 2 customer reviews
Some plastic fittings on the front passenger seat have failed. Several painted surfaces on the headlight switch, mirror switch and heating and A/C controls have worn off. The radio on/off button has come off. The front suspension needs relatively frequent repairs. The roads are terrible around here. Water pump and oil cooler replace at different times. The latter repair VERY expensive.
i love my a6

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