Hey all. My 2003 Mini Cooper is throwing a p2097 code it was throwing a misfire code cyl #4 I replaced the plugs in the car and the misfire code was gone but I can't get rid of the p2097 code. I know the code means "post catalyst fuel trim system to rich bank 1" I have 139000 miles on my coop. Any ideas what may fix it? Thanks.

 

This code signals a problem with your rear O2 sensor.

A rear O2 sensor code will not generally affect engine performance it only monitors emissions. It might hurt your gas mileage though, and you might fail and emissions test if you don't get it fixed.

Most likely you need to replace your O2 sensor, these things do go bad from time to time, it isn't that rare.

I have seen and heard that replacing the front one will cure this too. I know it sounds odd but it does happen.

 

Also there are many reasons why it's running rich... faulty injectors, leaky exhaust, faulty front (pre-cat) oxygen sensor, mods. Usually the auto parts store code readers will not clear the code, even if you have fixed the problem. You might have to go to a dealer or independent shop that deals with BMW will have the right equipment.