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I have a service engine soon light going on 2-3 months after having the car into the dealership for routine oil, inspections, etc. My Peake Research meter tells me that the code, B2 and B3 indicate "catalyst system efficiency, bank 1 & 2." The car has 60k miles on it and is well taken care of. It has dealer installed Dinan Stage 2 software, header and exhaust plus dealer installed Valentine 1 and XM/Sonos. I am currently experiencing no performance issues. I am stumped. Any comment? Thanks. Tom
 

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I have a service engine soon light going on 2-3 months after having the car into the dealership for routine oil, inspections, etc. My Peake Research meter tells me that the code, B2 and B3 indicate "catalyst system efficiency, bank 1 & 2." The car has 60k miles on it and is well taken care of. It has dealer installed Dinan Stage 2 software, header and exhaust plus dealer installed Valentine 1 and XM/Sonos. I am currently experiencing no performance issues. I am stumped. Any comment? Thanks. Tom
I would guess your headers are flowing more exhaust, which is outside the parameters the rear cats are programmed for. You don't say which headers, but the simplest solution is have your DME tuned to eliminate the code for rear cat seeing exhaust flow outside the parameters.

BTW, how long have you had the codes? You do have a Peake code reader to reset the codes, right?;)

Regards,
Jerry
 

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Those codes are quite common and are quite difficult to correct, it seems. I have the B3 on and off but it doesn't set the CEL on its own. Only when the B2 comes in very rarely as well does the light come on.
The DME sets these codes because it is seeing normal activity from the pre-cat O2 sensors but abnormal activity from the post cat O2 sensors indicating the cats aren't converting properly. So one option is to replace the post-cats, and if that doesn't fix it, then replace the pre-cats.
But a better option before you do that is sailor's "cat burn-out" drive sequence. 20 minutes down the highway in 3rd or 4th gear keeping rpm at 4000. It significantly reduced the frequency of my B3 code.
There have been threads on here saying that a cool running thermostat will cause these codes. Have you checked KTEMP is staying 78 deg C or above?
Very last option, and don't let the dealer talk you into this prematurely, is new cats.
 

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Do you have aftermarket headers with stock cats? That could be your issue.
 

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Discussion Starter #6
Thanks for that, the header and exhaust are all Dinan. I just started to get these codes. T.
 
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