I have installed a used TaipanXP turbo back exhaust on my 2003 WRX, the car is much faster, drive great and pulls hard but I have a check engine light that comes on only when I am granny shifting the car or when I am on the highway at about 60-65 mph. The code is a P0420 “CATALYST EFFICIENCY BELOW THRESHOLD (Bank 1).... Bank one is the passenger side exhaust ports.

Please give me some suggestions I have already replaced the o2 sensor and don't want to spend more money if not needed.

 

turbo back exhaust i'm guessing a downpipe came with this package?

You'll need a cell fix for the o2 sensor.

 

03 impreza Al is correct.

 

I should probably also add that I do have a leak in the stock up-pipe. It is not very big but it is there. Could that be the problem?

How do I know it is not my cat that has failed?


Yes the down pipe came with the package

 

take it to a shop and get it looked at professionaly. otherwise you will get a bunch of well educated guesses.

 

you DP and catback didnt come with a CEL fix?

 

I had the same code but my exhaust pluming was all stock it was bad fuel for me,cause the air fuel ratio was off and it was setting of the cel, for you you may need a cel fix if you do not already have one.You up pippe you shold get that fixed before it becomes a bigger problem.

 

Yeah, I talked to a Subaru speed shop guy and he said that I need a CEL fix as well. He said to go get a spark plug extender at the local parts storeand install it in the hole and then put the 02 sensor after it. Did it yesterday and so far so good.

 

never thought about that.

 

What would happen if I don't get the up-pipe fixed?

 

no that code is ur post cat o2, u've only got two sensor one in ur up pipe which is ur A/F one and the post cat one. get a cel fix or dont worry about it i got it cuz i got cel fix and went bakc to a catted DP. its not hurting ur car

 

thanks for your info!!!