I first tested the (new) Bosch O2 sens. according to my Haynes manual and it failed 2 out of the 3 tests. 1st test was sensor voltage during low/high rpms after engine warm, should have been <.5 idle to low rpms & > .5 during higher rpms. Never got above .016 volts. Next test it failed was heater circut never went closed loop to even get an ohms reading, let alone the specified ohms reading it needed to properly function. The only test it passed was no continuity between lead A and C/D. Voltage to the sensor passed as well. I suspect the heater circut is the one that was kicking the 43 and CEL since the ECU wants that heater circut closed loop after so long. Just my suspicion, I don't know those things all that well. Took the Bosch back to Advance Auto (with the recipt), explained my situation, they gave me credit for the Bosch and they had a Denso on the shelf, I walked out $5 ahead of the game and better running, no CEL Accord. Hope this can help someone out there. Somick, You were right on.