Hi, I’m looking to replace the rusting catalytic converters on my Impreza GX Sport with a full decat pipe. Like the one I’ve found here from Exhausts UK:

SUBARU IMPREZA SPORT/GL 2.0L DE-CAT EXHAUST (Non Turbo) on eBay (end time 07-Nov-09 09:44:40 GMT)

There’s just 2 things I’m concerned about which I’m hoping someone can shed some light on.

1.I’ve had a look at the first cat on my Impreza, and as well as the usual lambda sensor being in place (as normal), there seems to be a SECOND lambda sensor at the back of the cat! What the hell? The above decat pipe has a hole for the lambda sensor to go but what do I do with this mystery second plug? What is it?

2. Does fitting a full decat pipe throw up any check engine light errors etc? I mean, what does the lambda sensor think of the whole “cat-not-there-anymore” situation?

Cheers for any help and info guys.

Tom

 

Must be a closed loop lambda circuit then, so don't quote me on it but it may put your check engine light on as both lambda sensors will read the same, there not supposed to. You could get cat efficiency codes and lambda codes.