|Quote, originally posted by MacDalund »|
|My CEL was on and I've just replaced the o2 sensors as a result. I threw P0420- the dreaded cat code. The CEL just came back a couple days ago on and I'm getting VAG-COM'd tomorrow. I'm at 121k on the stock cat. I'm now pretty sure the cat is going bad.|
You aren't going to get rid of the P0420 code by changing the O2 sensors. You must have an aftermarket exhaust. There was a post awhile back about this. You need to use spark plug arresters to space the O2 sensor out farther. With the increased exhaust flow, it throws off the readings. I tried finding the post but couldn't.
As for the original poster, please stop trying to guess what the problem may be and get your ECU scanned. That is the only way you're going to know what's up with your car. You can guess until you turn blue and you've spent all your money and STILL not know if you solved the problem. Before you change any parts, save yourself some time and money and get the ECU scanned.