My Mom's 2000 Pathfinder

[jd07zjguy]

So for the last couple years when i have been at school my mom has had problems with codes in her 2000 Pathfinder. The code calls for the right rear o2 sensor (her model has 4 sensors) And this has caused her to fail emissions. So she brought it to a shop and they charged her like 180$ to replace the sensor and resets the pcm. A few hours later her light comes back on and she brings it back to the same shop a couple days later where they charged her another 180$ for the same exact sensor they just replaced!!!. AGAIN immediately that same code goes off not too long after getting that replaced.

Fed up with them she goes to a family friends shop where he replaces the MAF sensor even though the code was still for that rear o2 sensor. And guess what? Light comes on again!

So she goes to the emissions place and fails again with that same rear o2 sensor code. Needing only to have spent $150 at a shop from their list of shops to get it to pass, she did all this. Having spent a couple G's now instead, they waived her car.

So still with the light on she brings it to a third shop just a few weeks ago and they replace the catalytic converter which holds this o2 sensor. The guy working there was a nice guy and said that if the light comes back on for this code to bring it back and he would try something else free of charge.

So 2 weeks later the light comes back on. She's gonna have the guy look at it again since he's not charging her for that.

ANY IDEAS what could be causing this? My mom already said from now on shes just gonna pay the minimum amount on parts and get it waived but really wants a direction to go with all this. I searched some nissan forums and found some people with similar problems to no avail.

And i thought i have been putting a decent amount of money into my jeep.

ohhh and the worst part is that o2 sensor doesn't even effect the AF ratio at all. Its sole function is to make sure the o2 sensor is in working order. Which has also been replaced

[GreenZJ]

Id say move to Ohio where we dont have emmisions checks haha

[Saleen4971]

the reason i shy away from nissan is because they have electronic issues (sensors and PCM issues)


i would assume that they would check the wiring, and sensor outputs before throwing parts at it, but who knows.

[273-4]

I think the rear O2 sensor actually measures the efficiency of the Cat. If the rear 02 sensor doesnt see the correct level of CO2 and temp coming out of the substrate it throws a code.

[squashman702]

This thread is worthless without pics of mom.

[Ninergrad]

Well on toyota it throws rear O2 sensor if you have exhaust leaks. On 2000 pathfinder I will bet there will be some.
Check for exhaust leaks, you don't need a shop for that, just jack it and crawl around when it is running. I will also bet your O2 sensors are fine, but if you have exhaust leak, levels of CO2 will obviously be incorrect, causing the check engine light to come on.
There's no code for exhaust leak AFAIK, so O2 is as close as you will get to it.

[jd07zjguy]

Originally Posted by Ninergrad

Well on toyota it throws rear O2 sensor if you have exhaust leaks. On 2000 pathfinder I will bet there will be some.
Check for exhaust leaks, you don't need a shop for that, just jack it and crawl around when it is running. I will also bet your O2 sensors are fine, but if you have exhaust leak, levels of CO2 will obviously be incorrect, causing the check engine light to come on.
There's no code for exhaust leak AFAIK, so O2 is as close as you will get to it.

Good idea. Ill check that out. Thanks

[Ninergrad]

Good luck man, those things can be a pain in the ass.