Sup i got a 97 a4 1.8t..love it, but my check engine light went on and my obdII says bank 1 runs rich does anyone know what i can possibly do or get done to fix this, i have already swapped the air filter didnt seem to help much, also i get bad gas mileage and reduced horsepower especially at low rpms, also my rpm gauge jumps when i cold start..any input is appreciated thanks guys

 

Print out the codes.

Most likes it is one or two bad pre-catalytic converter oxygen sensors.

If bank one is rich, most likely I'd replace the ox sensor on that side

 

yup o2 sensor or possibly maf

 

O2 sensor's really easy to replace and that's most likely your culprit. I just went thru the same thing.

 

thanks guys ill try that next..do you have steps for replacin the o2 sensor diy or a link you can send me thanks for tha help

 

Search the archives, or spend 15 dollars on a Haynes manual from Pepboys.

You will need the appropriate wrench for 0x sensor removal and a good strong arm. When you put the new one in, use antiseize grease on the threads.

See if you can find someone with a vagcom and check the sensor output.

 

If you plan on doing some of your own work ... get a Bentley manual. It's worth the $80.