The exhaust needs to be looked over carefully for hairline cracks in the vicinity of the B1S2 O2.
The P2270 diagnostic test is ran only upon initial decel, The PCM knows the post catalyst O2's will be driven rich.
It would be a pretty small leak, A big leak would cause a P0137 in conjunction with P2270.
Assuming OE sensors are being used.....Hard time believing you have 3-4 bad sensors (If I'm reading the original post correctly?)
Might be prudent to swap the 2 post catalyst sensors if no leaks can be located.
The HO2S Heater Resistance Learned Values are supposed to be Reset anytime a O2 is replaced, A often skipped procedure.
The P2270 diagnostic test is ran only upon initial decel, The PCM knows the post catalyst O2's will be driven rich.
It would be a pretty small leak, A big leak would cause a P0137 in conjunction with P2270.
Assuming OE sensors are being used.....Hard time believing you have 3-4 bad sensors (If I'm reading the original post correctly?)
Might be prudent to swap the 2 post catalyst sensors if no leaks can be located.
The HO2S Heater Resistance Learned Values are supposed to be Reset anytime a O2 is replaced, A often skipped procedure.