Ok I have been getting intermittent CEL for bank 1 threshold code. Replaced all O2 sensors but still getting it but only after about 30-40 min of driving 70-75 highway. Car runs fine but concerned what the ECU is doing after seeing that code i.e.making it Rich or going lean? Clear code and its stays good for a while then comes back up Car is 2012 with build date on Nov 11 with 37k miles. Any ideas or should I just drop big $$ on new cats. I want to keep it OEM as much as I can. Other than Ford who makes best direct fit cats?