Flyboy

I've been getting the cat ineffeciency codes thrown every few days since 'upgrading' to APR's v5.0 code from the old v3.3 Stage 2+. I'd been using a VAG to clear the codes/CEL but decided to use the Fault Code Erase feature of my APR chip since it is easier than hooking the VAG up. After doing so I'd noticed that the CEL hadn't come back for some time which was welcome, but a little odd.

Today I hooked up the VAG to do some datalogging and looked to see if there were any engine faults. To my surprise the cat ineff codes were there, but no CEL. Odd. So it seems to me that using the APR FCE feature cleared the CEL but did not clear the codes, or else somehow prevented the CEL from illuminating when the codes were thrown. I haven't contacted APR about this yet since they aren't in on Sundays but will be posing the question to them soon.

And while I'm on the subject of cat ineff codes here's another question. Some have hypothesized that since I'm getting the CEL with the Stage I/II code and cats I probably have bad O2 sensors. It seems unlikely that both O2 sensors would fail simultaneously. Would bank 1 and 2 have cat ineff codes thrown if only one O2 sensor went bad?

Blown Nogaro

I noticed that if the description of the DTC says intermittent, it doesn't throw CEL. It's freaking annoying because I have to VAG my car whenever CEL comes on to see if it is something else even though I know I will see the same DTC. I was thinking about a bad O2 sensor as well.