I have had these codes on and off for quite a while. From reading what they meant in the Bently manual I figured it was a bad downstream O2 sensor. I replaced it and the codes went away for less than a day. Figured the sensor may be faulty and replaced it again. It threw these codes immediately as pending codes.
I went back to square one and dug out my meter and my bentley manual, checked the internal resistance of all three O2 sensors I had in my possesion and occording to Bentley they were ok. So I dig a little deeper into the wiring scematics in the manual and it shows the B+ wire for the O2 heater coming from the Evap valve. Is this correct? The Evap valve powers the heating element of the pots cat O2 sensor..? That and has anybody dealt with this before?


2000 A4 1.8 TQ ATW