Now that I've got that overheating problem resolved (or so I hope ), I'm taking on that CEL. It's throwing a P0135, saying the heater circuit is malfunctioning on the precat O2 sensor. I'm going to go out tomorrow morning and test the heater line, making sure the resistance (30 ohms) is correct and verifying that the wiring is supplying power to the heater.

 

Knowing my luck, I'll probably end up having to replace it. Now there seem to be universal and OEM sensors available... with the OEM's being a straight plug-in replacement with the proper harness (and more expensive), while the aftermarkets seem to be a "solder/crimp your old harness on" (being less expensive).

 

Is that right? Any other differences? I have convienent access to a soldering iron, and not-quite--so-convienent access to a heat gun, so I could get the harness moved over to the new sensor without too much trouble. The hassle is worth the difference in price, from what I'm seeing.

 

Edit: Now I'm confused :-\. In the repair/diagnosis section of the Haynes manual, they depict the O2 Sensor as having a 4 wire connection. In the wiring diagram section, there's only 3. Oxygensensors.com lists both OEM and aftermarket sensors, but they're all 3 wire. Why the contradiction? I can hope that once I get out there tomorrow and look it over, it'll be plain as day, but right now, I'm confused.

I replaced mine with a generic from oxygensensors.com. The data sheet they sent was very informative. I think what the 4 wire sensors have is an extra ground, but I could be mistaken.

i don't have any explanation on the wiring, but you can have a look. look at the O2 sensor on the car and/or look at the wiring harness for the O2 sensor to see how many wires/pins it has. make sure the one you get from the store or order has the same amount. you could also stop by the dealer and have them pull one out for your car, look at the wiring and go buy it elsewhere.

 

i think i've heard of most people on here talking about 3 wire sensors, so that's probably correct.

Yep... mine's a nice three wire connector, set up in a triangle fashion. Two whites leads, one black lead. Tested the resistance on the white leads at 4.5 ohms (should be 30), so I'd say the heater is dead. Time for a new sensor *blech*.