I have a 11/07 built BF MK2 XR8 sequential.
I have recently have a new exhaust fitted, it still has the standard headers but it now has high flow cats, the mid muffler removed and twin 2.5" pipes in place as well as a red back muffler on the rear.
The car sounds pretty good but soon after i had it put on the engine warning light came on, i called ford and they said it isn't a big issue but do to the exhaust they wouldn't look at it under warranty.
Any ideas on how to fix this? cheers

-the oxy sensors have not been touched

Good idea to put it on a diag machine and get the fault code. Go from there.

Being a BF it has 4 HEGO's. The aftercat HEGO's are a diagnostic to the cats, ie they check that they are working properly. Most high flow cats do not work as well as the originals because quite simply, they all about flow and not very good at actually catalysing the nasty stuff. Often these aftermarket cats have poor heat insulation which, combined with a large internal structure make for not enough temperature for them to work correctly.

as pete said, your ecu thinks your cats arent working correctly hence the warning light. If you were to get the car tuned your tuned could turn off the warning light function for you. My BF XR6T had the same issue with fittment of a hiflow cat, retuned, more kw's and no pesky light





-mitch