http://www.brickboard.com/RWD/volvo/1239422/220/240/260/280/oh_boy_go_engine_wiring_harness.html

I'm trying to track down a bad idle until the car warms up. I replaced the harness a couple years ago in my 83 245 which doesn't get driven much, a project. I was reading up on 02 sensors and found this link above with the same question I was searching out. The new harness I used has a plug for a heated 02 sensor. I put a new sensor in without the heated wires, you know the cheaper one wire sensor that originally came in the 83. My question at the moment is can that plug cause the ECU to misread or mis-diagnose the 02? Should I not have that harness in the car (did I get duped on another ebay purchase?) or would the ECU even recognize a heated O2 sensor if I placed one in the header pipe? I've been chasing this bad idle for some time and it goes away when the car warms up and is driven a couple miles. I've found vacuum leaks and replaced the intake gasket. Still it seems to be something else. I'll try to unplug the sensor tomorrow and see if it changes the idle. Just thought I'd check with the brickboard gurus.