I've got a 940 station wagon, '93 2.3L regina. I've used brickboards multiple times in the past to fix various problems that i've had but I couldn't find a quick fix on this one so I was hoping someone could give me a hand.

My car would start, idle well for maybe 35 seconds, and then start idling badly. It then lost all power when i tried to drive, sometimes stalling. I looked through the various posts and thought it might be my O2 sensor. Sure enough, when I disconnected the O2 sensor the onboard computer just compensated and the car is working fairly well. I measured output from it at a constant 45mV, which I took to mean that the sensor had stopped responding and was no longer good. I continued to drive my car and ordered a new O2 sensor through ebay. Today I hooked it up and the new sensor does the same thing. the car runs fine, I hook the unit into the wiring harness and then the engine begins to sputter and the car gets no power. I disconnect it and the problem is solved.

The idle is 200rpm higher than before and much less stable than usual, the engine sounds like it's running rougher, and I'm loosing fuel economy, or else I'd just leave it disconnected. I also read that you can damage your catalytic converter when the computer defaults to an overly rich mix.

I have some theories, like maybe the onboard computer is messing up (though it seems to run the car well enough without the sensor), or perhaps the small leak in my tailpipe about 1 ft. before the sensor is causing too little exhaust to pass by the sensor, making it report incorrectly (though again my car was running fine with said leak until a few weeks ago).

One final caveat is that the engine light was on for several weeks before the engine started acting up, so I'm not sure if the computer sensed the sensor was dying and that's why it lit up or not. Even with the new one in and after pressing the button by the clock the light stays on.

Anyone have some ideas what I might try next?