I am thinking the sensors are first. At the start, Trixy wouldn't pass smog due to random misfire. Plus, there was loss of power on hill acceleration. Replaced the timing belt at 70 thou and the misfire.cleared up, car runs great. Now there are the O2 codes which had been masked by the misfire apparently per the dealership service dude.I am late to the party, not sure how I missed the Notif, sorry prime.
But, i would be super super surprised if that is a computer issue. That code is almost always the O2 sensor. If you replaced the cats, whatever damaged those could have easily damaged the sensors. I would gamble that first for sure. change them, clear the codes, drive.
You can get a used ECM (on board computer) on eBay pretty easily.
But I really dont think thats the issue. Have you or your mechanic looked for damaged wires, etc?
Also, did it start showing these codes shortly after the cats were changed? Have you ever cleared them, driven then seen if they come back?
Gotta be those sensors
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