What would happen to my O2 sensor if I got 2 of the wires mixed up? The previous owner picked up a generic O2 sensor and cut the d@mn harness and hard wired it to the existing wires. When I got it, 2 of the wires were loose. I just reconnected them, was a total guess. What if I got the wrong wires? (the 2 that were off were the yellow wires, dont know if that helps...) My truck has been averaging about 13-14 Mpg driven modestly. And before there were reports of it getting up to 17. Do you think I got the wires crossed? This evening I'm going to switch them and see if it throws a CEL or runs better.

Any thoughts?

 

i wish i was getting 13 or 14 mpg. even after a tune up i dont get that.

 

Has anybody done this before?

 

Best bet would be to ask the manufacturer of the sensor what wires go where. You can get a wiring diagram from the FSM available in the FAQ section here, for the truck side of the harness.

 

Thats the problem, I don't have a clue who made it. Both wires are yellow also.

 

is it a two or four wire sensor?

Might be better off just picking up the right sensor for the truck, and order the harness connector for the truck end from the dodge dealer.

 

i don't know about your wire colors, but a typical 4 wire heated sensor is 2 whites carrying 12volts for the heater circuit, a ground, and a signal wire back to the pcm.

i don't think its a good idea at all to every randomly connect wires. if you're not sure, either do nothing, or probe the wires with a multimeter to identify which is which.... then connect them.

your expensive pcm is a terrible thing to waste.

edit

http://mr2.com/TEXT/O2_Sensor.html

http://auto.howstuffworks.com/question257.htm

http://www.ngksparkplugs.com/techinf...200&country=US

 

Its a 4 wire sensor.

Thanks for the info! I was wrong about the color of wires. The 2 that were off were white. there was a grey and a black wire that were already connected. So if this is correct "2 whites carrying 12volts for the heater circuit, a ground, and a signal wire back to the pcm." then It shouldn't matter how I wire the 2 white wires up. Either way, I'm still getting 12v to the sensor........right?

BTW, against better judgement, I did switch the 2 white wires and have not noticed any change in preformance and no CEL yet.

 

the whites are interchangeable, provided they are connected to the 12 v heater feeds from the source, whatever color that is. if not sure, test it.

gray is ground and black is feedback signal to the pcm.