My check engine light came on Monday night so I scanned it, catalyst system low efficency, cleared the code Tuesday morning and it never came back on until tonight, I'm going to rescan it tomorrow just to make sure its the same code but has anyone had the rear 02 go bad and throw this code?? Also has anyone just taken their car into an exhaust shop and had an after market converter welded in?? I just want to be rid of this stupid light but I want to make sure its done right and reading about the track record of cats on these cars would an aftermarket one be my best bet??

 

you need a new cat. You can try replacing the o2 sensors but the code will come back, so waste of money imo

p0420 means bad converter. Try picking up a used one with low miles, I got one for $100 and its been solid ever since.


http://www.audizine.com/classifieds/...e=1&perpage=12

keep a look out there. Used cats with low mileage pop up quite frequently for around $100.

 

and to answer your second question.. after market would be your best bet if you want a hi flow cat for more performance say coupled with a catback exhaust. It will cost you more.

otherwise stick with oem.