My 2002 Protege has been stalling when idling and running rough on take off. Once I get going It smooths out pretty well. A friend pluged his tester into the computer port under the dash and it showed p0140-o2 bank sensor 2, and po131-o2 bank sensor 1. I'm not a mechanic and I'd really appreciate it if someone here could tell me where they are located and how hard they are to install. I forgot to mention that it showed po300 misfire detected too, but the sparkplugs were bad so I changed them. That might have been the problem there. Thanks.

Bob

 

I'd be not so quick in replacing the sensors. Typically they are holding up quite well. You may be killing the messenger for delivering the news.

I would first make sure the basics are taken care of, such as spark plugs, MAF sensor cleaning, air filter, all vacuum hoses and connections seal and unclogged, EGR ports clean etc.

The message doesn't say the O2 sensor is broken, it says it reacted to something. Anyway that's my interpretation.

Everytime you make a change, turn the CEL off by taking off the ground at the negative cable at the battery and stepping on the brake for 5 seconds.

If the CEL comes back on you do another step.

The air intake hose is a common culprit: it cracks and lets in un-metered air.

Good luck.

 

Thanks for all the info tanprotege, I appreciate it. I'll check the the things you mentioned and go from there. Thanks again!

Bob

 

You are welcome. You can also go to carsurvey.org, '98 protege, "Lovely little runner",and read what I have done to get the light to stay out.
Your biggest problem is the miss-fire.

 

Yeah. I too was going to suggest the air intake hose. That seems to be a common "biggie" w/the Protege's.
Be sure to flex it when checking to make sure there aren't any hidden cracks in it.
They are around $75-80 from the dealer, but perhaps they are available on the aftermarket for less somewhere... like RockAuto.com?
Or perhaps there's an alternative to the factory hose?

Anyone ever tried replacing their hose w/a universal? Speak up, Boys.

 

Thanks once again tanprotege and thank you too virgin1. A quick look last night turned up a bad vaccume hose. I taped it for the time being and that seemed to help a little. I'll have time this afternoon to do a more thorough check. We'll see what turns up. I cant thank you guys enough for your help, It's really appreciated.

Bob