Just want ideas, reason, symptoms of why an Audi would run rich. I've noticed my mileage slowly decreasing. Apart from the cold weather factor, are there any VAG codes that would indicate something faulty? Thanks in advance.

 

black stuff from exhaust built up on rear bumper near muffler tip.

 

do you have a bov ? haha

 

there are codes for that like the ECT sensor and the O2 sensor but to get the codes you need to have it checked no point me just giving a list of couldbes

 

lazy but not yet shot 02 sensors can be a major cause. Bad plugs, boost leak, bad maf are another few reasons. Even a bad ects can cause a rich condition.... clogged cat, air filter change... yada yada

 

lol no BOV, its a 2.8. Not that there would be if I had a 1.8. Boost leak ruled out also. Yea I was afraid there could be many possibilities, oh well. I'll have the codes read soon.