I have a 2004 A4 B6 turbo with 85,000 miles. I am getting engine code 171 which is engine running lean, left bank. I am also getting engine code 507, engine idle too high. I have previously replaced the fuel injectors, checked for any vacuum leaks, and cleaned the K&N air filter. I ran injector cleaner through the fuel tank also. What is my next step? I understand the fuel filter is under the engine and a bit difficult to get to. Is that my next option?

Thanks.

 

The same thing happened to me, code wise. It turned out to be my pressure regulator valve/diverter valve, Just a heads up maybe thats what it is...

 

The fuel filter is behind the passenger side rear wheel, and takes about 15 minutes to change if you've never done it before (unless your lines get stuck). Its a very easy change.

 

fuel filter is loacted infront of the passenger rear tire. U can see it if u get under the car.

 

P0171 I think that's a vacuum leak isn't it?