Code 2, Oxygen Sensor on PW0 OBD0

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Mattyg2

Junior Member
I keep getting a code 2 on my PW0 OBD0 b16a setup in my 1991 integra, I know for sure its plugged up and i also get the bogging or hesitation when cruising. I've also switch the wires so many times and still the same. Even when i switch the wires it's still code 2 after resetting the ecu, why is it always code 2 and not code 1 for primary oxygen sensor if i switched them? is something wrong here? Well, I ordered a new oxygen sensor that should be coming in a few days so I'm hoping that works. Are there any other things i should look into also if that doesn't fix it?
 
You need to add a 2nd O2 sensor and wire it to the ecu or splice both O2 sensor wires together and run it on one O2 sensor . Im sure all JDM obdo ecu's run on a primary and secondary O2 sensor. Each one reads their own pair of cylynders. On your pwo ecu C8 (plug C pin 8) would be the secondary O2.
 
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or splice both O2 sensor wires together and run it on one O2 sensor
Bad idea. Even Hondata says so:

Tech - Closed Loop

Pre-OBD I Engines

Early VTEC engines use two oxygen sensors arranged to read one cylinder pair per oxygen sensor. The mixture for each cylinder pair is tuned separately. It is important not to wire the sensors around the wrong way, otherwise one cylinder pair will run lean, and the other pair rich. It is also important not to wire one oxygen sensor into both sensor inputs, otherwise the engine will run either very lean or very rich.
 
Yeah definately do not splice both o2 wires together just run a single wire from ecu Pin C8 to sencondary o2 sensor. If its plugged then unplug it and use a single wire o2 sensor which you can pick up for around $20 new.
https://hondaswap.com/parts-sale-trade-wanted/conversion-harnesses-4-sale-143438/
i've bought new o2 sensors and i still get code 2, even when i switch the wires it still comes out to code 2! and i get stupid bogging when crusing. i don't get what the problem is and i'm stumped
 
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