1999 Audi A6 Quattro Repair and Maintenance

A guide to problems, costs, maintenance and repair for your 1999 Audi A6 Quattro

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1999 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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1999 Audi A6 Quattro Questions

Can the computer be fried? (3 answers)

After a battery install, the car wouldnt excellerate. Mechanic ran diagnostic, but couldnt communicate to computer system at first. Then one code showed. Throttle body. Throttle body changed, brand new, still wont hold excelleration. Could it be a bad code and computer symstem is no good anymore?

rear window replacement (1 answer)

is a 1998 a6 station wagon rear window compatible with my 1999 a6 station wagon?

my car will crank but wont start (1 answer)

I was told the timing belt could be the cause or the spark. the Previous owner said the engine went out while it was running. I need to know the steps to fixing it and if it will be an easy process or too expensive.

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1999 Audi A6 Quattro Reviews

Rated
based on 3 customer reviews
tranny doesnt seem to be shifting manually or automatically floor boards got wet at one time heard tranny solenoids are below driver seat is this true and what possible repairs can i look at,not a mechanic either
I have had this car for almost 3 1/2 years now. Bought it used at 119k miles and have since had a couple of the 100k problems expected with normal wear and tear. We have put a little over 60k miles on quattro since we adopted her and still love it. The interior allways impresses, and I would and have reccomended this car to a friend. Friend finally saw the light and hung up the subaru keys ...
I bought my 1999 Audi A6 Avant at 90K and it needed to have the coolant fan, timing belt, ball bearing on front right axle, and some other stuff replaced. Since purchasing the car for $8,600, I have paid almost $4,000 in various repairs (about $500 was due to vandalism), but after all of that it drives like a charm. A smooth, quiet ride with a hefty get up and go for a ten year old car. I also ...

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