V8Brah

I have an IS500 but figured there'd be more technical knowledge offered in this IS F subforum. I’m getting an intermittent CEL with 2 codes: P0420 (low catalyst efficiency bank 1) and P013A (rich to lean, slow response bank 1 sensor 2). I’m 99% certain it’s caused by my aftermarket catback exhaust because I can see a large gap between the flanges of the driver’s side primary cat and downpipe, and occasionally feel air when it's revved if I stick my hand under the flanges. I’ve never noticed any issue with performance or loss of mpg, other than a strong exhaust smell outside of my car (not a sulfur smell) which comes and goes. I’ve had the exhaust for only about 1500 miles so far but the CEL started about 300 miles ago.

My question is, is long-term damage due to these codes/exhaust leak being done to my engine? Is the bad reading from this downstream O2 sensor actually providing feedback to the PCM and injecting more fuel than necessary to harm the engine and cat? OR, is it purely used for emissions? Obviously I plan to fix this (I’m working with the exhaust manufacturer), but I’m just wondering what the severity is here. Honestly, makes me want to not drive my car for the time being and I'm wondering if there's rationality in that. Thank you!

inovashn

curious which exhaust you went with?

lobuxracer

iTrader: (2)

Not hurting anything long term, just making it impossible to pass an OBDII based smog check. The ECM doesn't do anything special when the DTC for catalyst efficiency is tripped. If you were having sensor 1 issues, that would be totally different. It's a wideband sensor responsible for trimming AFR.