Co2 Sensors - Non Techie Needs Help Please !

[dodo1]

I've read through the threads but still need help. My '96 XLT Explorer has had the Check Engine light on for a couple weeks. Thought it was a faulty fuel cap, but recently took it in for diagnostics. Told it was the CO2 sensors, and was quoted $$$$$ to replace. Mechanic says need not replace (on such an old vehicle), but will cost more to run. My questions.....what should a sensor cost (I'm assuming I need two of them)....and how much labor and expertise is required ? I realize I'd need the special tool to replace them myself....would it still work out more economical to buy the tool and sensors and attempt to replace them ? How much fuel economy do I stand to lose if I ignore the problem (I travel about 200 miles per week). I've just spent $1500 on other repairs, so was hoping to keep my truck going for at least another year. Any advice offered is very much appreciated. Thank you.

 

[IZwack]

Are you sure they said CO2? Because usually its the O2 (oxygen) sensors in the exhaust.

Anyways, Oxygen sensors are typically $45-$90 USD ($53-$110 CAD) from your local parts store.

 

[dodo1]

My mistake...I'm sure it's the O2 sensors. I forgot to ask another question before....do these sensors affect the outcome of Emissions Testing if not replaced ? In Ontario vehicles are testing every two years....my truck is due. Do the sensors help to limit pollution from exhaust emissions ? If so, I'll have to replace them anyway. Just looking for the least expensive route. Thanks.

 

[IZwack]

The oxygen sensors are used to adjust for the proper air/fuel ratio. So yes, a malfunctioning oxygen sensor will affect emissions -- it should also throw a check engine light (CEL).

 

[BobWiersema]

This is the tool I bought to replace mine.

It cost about $20. My 98 xlt has 4 sensors. Look under the car and see if you have 2 cat.converters, if so you have 4 sensors. I would replace them and reset the PCM to get the mpg's back up. And yes you may not pass that smog test with that error, although you may be able to fake your way through by resetting the PCM and driving directly to the test station. Not sure? It may work.

Bob

 

[gavin]

the scanner should have said WHICH O2's are giving bad readings.

since there's 4, I wouldn't want to go spend $200 and replace all 4 when it's not necessary.

I also just used a 7/8" open-end wrench.

a stubby wrench would be easier for the downstream sensor on the dri. side, although I'm not sure they're in the same spot between the V8 and V6'ers.

 

[KPT]

I don't think the 4.0 has 4. Mine has 2 but thats OBD I. The 4.0 doesn't have duals to the muffler like the 5.0, I think its 3 for OBD II.

Autozone rents the open socket. I have no idea if they are up North though. I put the front tires on a hill and had plenty of room to change the O2's. That was before I was lifted too.

 

[dodo1]

Thank you to everyone who replied. All great information, glad I came to this site. Happy to say I fixed it with your help.