99 Civic Special Edition D16Y7.
Problem is primary O2 Sensor heater problem CEL up. 've tried 2 used O2 sensors from other wrecked Civics with no luck. I pulled out my Honda Service Manual and followed the troubleshooting guide somewhat for this CEL. First check is dsconnect the sensor and measure resistance of pins 3 and 4 (heater), it's suppose to be 10 to 40 ohms and it measures at 20 ohms so no problem. Next check is measure pin 3 and pin 4 each to ground to check for shorts, suppose to be no continuity to ground and there isn't. Next check is to check for battery voltage on cable connector pins 3 and 4 with ignition at on (II) and there is battery voltage. The next steps I haven't done yet as it involves disconnected at ECM/PGM and checking for bad wiring and possible bad EGM/PGM. I did however check for power at pins 1 and 2 (sensor) with ignition off (0 volts) and at on (0 volts) and running (0 volts). Is the O2 sensor self powered, generate it's own DC signal? I checked the sensor connector with engine running and pins 1 and 2 did slowly build up to around 150 mV. With the engine revs up it was all over the place even going negative. Does anyone have any experience with any of this and could share. Thanks in advance.

 

Yeah the O2 sensors will produce there own voltage. Typically they should switch from about .2mV to about .8mV (+ or -) and average something like .45-.46mV and do it at about 5-6 times a second.