I got a P1166 and P1167 code on my 99 Accord. I have replaced the Primary O2 sensor and tested the secondary O2 sensor. The orignal primary sensor had an "open" circuit on the heater leads (no resistance=heater circuit blown). I intalled a new sensor and re-set the computer. After starting the car, got a P1167 (primary O2 sensor heater malfunction) again. The O2 sensor tests good using a "out of car" propane torch test, and the heater circuit leads have ~9 ohms so the heater looks good. With the sensor installed, when I first start the car, I have approx. 0.3 volts on the signal leads, then it drops to 0 volts at the same time the check engine light comes on. I can unplug the sensor from the harness, and it shows 0.9 volts with the car running, but goes instantly to 0 when I plug the sensor back in. The heater circuit has approx 12 volts on it, so the heater circuit fuse is not blown. Has anyone seen this? The sensor I bought looks just like the factory one, but is a "universal" type from Bosh.