I purchased a used 2002 A6 3.0 in December. Within 1 day, the check engine light came on. I brought the car back to the dealer, and he claimed the problem was fixed after holding the car for multiple days. I picked up the car, and before I got home, the check engine light was back on. Since December, the vehicle has been at the dealer 4 times with the same issue(we pick up the car-light is off-drive a few miles-light comes back on). Earlier this week, the dealer callled and said the issue was finally found-a transmission valve was stuck open and needs to be replaced. Has anyone ever heard of this, and does this negatively affect fuel economy as the dealer states? At this time, the car gets no more than 17 MPG, even on the highway. If someone has some knowledge and/or experience with this, please let me know. I love the car, but my wife is so frustrated, she wants to return the car to the dealer. Thank you.

 

There are about 6 valves in the transmission. Their actuation is what shifts gears and locks and unlocks the torque converter. A stuck valve can result in missed shifts or a torque converter which will not lock. These failures result in very specific OBDII codes telling the dealer exactly which valve is not working. They can then connect to their diagnostic equipment get more detailed information like whether it is intermittent and when the first fault occurred. The first time something like this happens the dealer will typically read and reset the code and go for a one mile test drive to make sure it does not come back on. That may not be enough to warm the transmission adequately to cause the code to reoccur. They will then call you and tell you your car is fixed and send you on your merry way. Once it happens a few times they start to get serious and look more closely at the problem.

If the problem is a stuck valve they fix it by removing the transmission oil pan and taking out and replacing the Mechantronics unit which contains all of the valves and actuating solenoids. A transmission shop will rebuild these units and reinstall them, the dealer will probably install a new one from stock. This is about the only transmission service which can be performed without removing the transmission from the car. Their cost to fix the problem is probably $600 for the Mechatronics unit (cost) and about 4 hours of labor. Figure $1100.

Make sure they fix this problem. Sometimes what they think is a stuck valve is a more serious problem in the transmission and you want to make sure they repair it before you are on your own. If the valve is stuck open because it is worn that is no big deal but if it is stuck because of debris it could indicate something else internal is failing. Tell them you want them to inspect the transmission fluid for metal particles during the service.

 

Return the car to the dealer. An Audi is not for you. They are too costly to maintain.

Bob