Im battling a P2099 code, post cat fuel system too rich, bank 2. Been erasing the code with a hand held but this is getting annoying.

My question to the tuners is does the rear sensor have any control over air / fuel mix? I know for years it did not but searching around I do see it has some control on some vehicles nowadays.

Im also wondering if the dealer installed any software updates during any dealer visit could it have effected my EVOMS flash? Note no update was noted on any paperwork from the dealer.

Last night just before it threw a code, 3rd and 4th gear did not pull hard at all, car made full boost (on the dash) but would not really accelerate, seconds later the CEL came on. I cleared the code and then the car ran fine.

Sometimes before even with the code on the car run fine, really strange.


I have the EVOMS tune and Cargraphic Loud exhaust FYI.

I do have some of those bigdaddies o2 extensions with mini cats in them en route and will test accordingly.

Some side notes and things performed to try and isolate the cause:

24k miles
stock filter
MAF have been cleaned with CRC
Plugs recently changed
two new post cat sensors installed
bung extension tubes installed but did not fix
Cats were inspected at RSS w/ a scope and looked fine.