zerophat

05 - B6 S4 with stock exhaust.

I know the exhausts get dirty, but been noticing heavy black residue in both tips, even right after they are cleaned after a drive.

Wondering if that is a bad sign, to make a trip to the shop. No error codes, no unusual smells.

Any suggestions?

Audinado

Have you put engine oil lately on the car? Sometimes when you put more oil or overfill the normal levels that can happen.
Otherwise if you are not getting any warning but you want to make sure you can call your independent mechanic or Audi dealer.

Good Luck.

Peter Badore

Coolant temp sensor could be out of specification but not yet enough to set a DTC? Could be running too rich with an incorrect temp sensor. Many A4s and A6s
exhibit this behavior but there are are other causes as well.

vg8s

Your MAF Sensor maybe on its way out. i was having plume of smoke and black residue on my tips. changed out my MAF and no more running rich and no more plumes of smoke. just my opinion.