My CEL came on just in time for winter. 1998 A4 quattro, 5 speed, 130k miles, chipped, milltek exhaust, carbino intake, apr hoses, apr diverter valve. Got the following codes, also have noticed a drop in power:

P0401 - EGR flow insufficient

P0171 – System too lean Bank 1

P0174 - system too lean Bank 2

P0300 – Random/Multiple Cylinder Misfire Detected

P0302 – Cylinder 2 Misfire

P0303 – Cylinder 3 Misfire




Misfires could be spark plugs or coil packs, but I don't know about the others. Not sure if one thing can cause all those codes or if they are related. Any ideas about what it could be? I will clear the codes and see if they return or not.