My 2000 A6 2.7T keeps indicating a problem with the engine (dashboard indicator light showing the engine with an electricity symbol over it). My mechanic plugs in his diagnosis tool and it tells him that the car is suffering from a vacuum leak on both banks of the engine. Having investigated the apparent problem at great length, both visually and with a smoke device, he can find no such leaks. He has re-set the computer several times and all is well for a few miles, after which the light comes on again.

I don't want to go through the process of buying numerous different parts until I find out what is wrong and I'm hoping someone may have had the same problem and can lead me to the most likely cause/solution.

Thanks

 

whats the code

 

I don't know - the guy at the garage just showed me the hand held device that was plugged into the car beneath the steering wheel that showed there to be a "Vacuum Leak" on both left and right sides.

 

Check to make sure you diverter valves hold vacuum. They are under the triangular cover on top of the engine and will leak internally so you wont see any smoke.

 

might need a new vacuum pump. currently i have the same problem on my a6 4.2. shows a failure in bank 1 and bank 2. forgot the error code.

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On the v8's the common vacuum failure is the intake manifold changover valve. Theyre on the front of the engine. They have a rod connected to them and both should suck down on startup.

 

in front of the engine is the throttle body check the rubber boot where the intake for the turbo gose if there is a crack it is a comon problem if ok check mass air flow sensor or tell your mechanic

 

I don't recall the codes....but if it was lean codes on bank 1 and bank 2....... a MAF took care of the problem for me!! but of course make sure that you check ALL of the vacuum lines and intake boots first!!!