Which parts fail
Components named in complaints (fuel pump, injectors, fuel tank, hybrid and EV propulsion).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 1999 Audi A6 owners, lightly cleaned up (personal details are redacted by NHTSA).
Fuel leak from supply fuel line in an 1999 Audi A6 during very cold weather. When temperatures drop below 15-20 f the crimped end of the fuel supply line leaks fuel, which creates an intense fuel smell in the cabin, but only if not moving at high speeds. The fuel leaking from the hose travels towards the back of the engine and eventually drips onto the exhaust manifold creating intense smoke. Apparently the cold line intensified by super cooled gas streaming through it causes the metal part of the line to contract at a sufficient rate as to allow fuel to leak out. When the fule line warms up, the leaking stops. Dealer could not replicate the problem because the ambient temperature was 40f at the time of testing and hence refused to aknowledge the problem. Subsequently the problem re-occured and I took several close-up pictures showing the leak and the ambient temperature. …
I have recently experience the exact same sudden acceleration with my Audi A6 quattro. The temperature outdoors was very cold and I was traveling up a hill when the car kept accelerating on its own. While applying pressure to the brakes the car continued to accelerate. Luckily I was able to pull the car off the road and shifted into park. Upon placing the car in park the tachometer red lined. After taking it to the garage the technician determined he could not find anything wrong the automobile. The following week my husband drove the car and experienced the exact same thing. Again our car is in the garage and the technicians are trying to determine a cause. To date, they have been unsuccessful in finding the problem.
Consumer received one of several recall notifications from the manufacturer, and took the vehicle to the dealer, who wanted for consumer to leave a credit card and then they will repair all defects, even those not related to the recall, and charge consumer additional expenses not in conjunction with the recall. Recall campaign NHTSA campaign id number : 01V157000 consequence: running out of fuel without warning while the fuel gauge indicates that there is sufficient fuel in the tank lead to safety problems. Vehicle ABS light was on.
When filling the gas tank in my 99 Audi A6 quattro pressure builds inside the tank and sprays back at me. This has happened each time I put gas in it full or not. A recall was made but, not for my VIN. I spoke with a Audi rep. And a dealership and they said there's nothing that can be done unless I pay for it. I would but, there is already a recall made for that car just not that VIN. It's a hazard and I've had other problems that I paid for. Please let me know if anything can be done. Thank you for your time!
Car accelerate on it's own. About 15 minutes into trip, started to feel the car accelerating on it's own. When I let go of the accelerator, RPM did not drop. Double check the cruise control, turn it on and off makes no difference. Pull off road, put in neutral to stop, race to 4K RPM. Restart car, still @4K. Stopped for 5 minutes, restart, back to normal. An accident waiting to happen!
Have had nothing but problems with the Audi A6 since inception. Car started making a horrible noise that sounds like it is coming from engine or transmission. Car cannot pass emissions. Engine smoking fluid is pouring out of front of transmission. The car dealer: nalley Audi in roswell, georgia. The car dealer nalley Audi fraudulently took money from me and never repaired vehicle.
Vehicle fully accelerated on it own, resulting in very high speeds in traffic and on downhill drive. Very difficult to stop vehicle when careening down steep hill toward an intersection. Reportedly can happen in cold weather at any time. Dangerous!!
On January 19, returning home from a family trip, the throttle on our 1999 A6 stuck open at 65mph. I was trapped in the left lane of a 4 lane highway with no shoulder to pull onto due to heavy snow accumulation. I had stand on the brakes as hard as I could to avoid smashing into the vehicles ahead of me that started to slow down for an upcoming speed zone. I overheated my brakes almost to the point of failure in order to pull into the right lane and make a quick exit where I turned off the key. My brakes smoked and smelled for about 15 minutes in zero temperatures. After letting it sit for a while I tried to start it again and it immediately redlined. We were eventually able to restart and drive the car home at a very slow and cautious pace using back roads. This was a terrifying and very dangerous, life threatening situation for my self and my family. …
Gas guage red half full when tank empty. Car lost power when it ran out of gas on a remote section of highway causing an unsafe condition. Manufacturer aparantly was aware of defects in the electrical unit in the gas tank caused by fuel additives in the us. Notice should have been given to owners, even if no recall was planned as the units seem to fail intermitently. Company appears to be trying to ignore a problem they could fix with one mailing to its customers...
This, and apparently most, Audi A6 vehicles do not have functioning gas guages. As a result the driver does not know when the vehicle will run out of gas. I have run this vehicle out of gas 5 time since the problem began, the last at 65 MPH in the fast lane of ca 101 freeway. The sudden vehicle slowdown almost caused a multi-car, high speed accident. Audi has repeatedly attempted to fix the problem but after 8 months, report that they do not have a fix available.
Related recalls
Fuel system, gasoline › Storage › Tank assembly
Vehicle description: passenger vehicles. Sulfur in fuel interacts with certain additives found in widely available gasoline causing sulfur to become deposited on the contact points of three fuel sending units mounted inside the fuel tank.
Remedy: Dealers will remove the existing fuel level sending units and replace them with fuel level sending units using a new alloy composed of gold, silver, and a small amount of nickel, which will not chemically react with…
Fuel system, gasoline › Storage › Tank assembly › Filler pipe and cap
Vehicle description: passenger vehicles equipped with quattro drive system which employs a fuel and fuel vapor leak detection system. If the vehicle is refueled shortly after the engine is started, and is kept running while being refueled, the fuel vapor recovery system could produce sufficient back pressure to cause fuel to be…
Remedy: Vw is providing a new page for the owner's manual and also requesting owners to make an appointment with their dealers to have a label containing important refueling instructions installed inside of the fuel filler…
NHTSA investigations
Stuck-open throttle
Complaints received by odi and Audi allege that, in extreme cold weather, the throttle May unexpectedly fail to return to idle when the accelerator pedal is released, making it difficult to stop the vehicle.in March of 2004, Audi performed a series of tests to investigate the possible causes of throttle icing.Audi concluded that under certain driving conditions - only short distance trips over several weeks where…
Stuck-open throttle
Vwoa has recalled approximately 28,300 my 1998-99 a6 vehicles in cold weather states that experienced the highest rate of throttle icing incidents in the subject vehicles (04v-495).the failure rate in the a4 and passat vehicles is much lower than in the recalled vehicles.odi will continue to monitor the experience in the a4 and passat vehicles.the closing of this investigation does not constitute a finding by NHTSA…
Fuel System complaints in other A6 years
Frequently asked questions
How common are fuel system problems on the 1999 Audi A6?
NHTSA has 39 complaints about the fuel & propulsion system of the 1999 Audi A6, 18% of the model year's 217 complaints. The component named most often is storage › tank assembly (17 mentions).
Is there a recall for 1999 Audi A6 fuel system problems?
Yes — NHTSA recall 01V-157 (tank assembly, May 3, 2001); NHTSA recall 99V-058 (filler pipe and cap, Mar 22, 1999). Recall repairs are free at authorized dealers.
At what mileage do 1999 Audi A6 fuel system problems start?
Half of the complaints with a recorded mileage happened before about 84,000 miles, and 13% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.