I have an 07 LX with 82K miles. My check engine light comes on intermittently and I had it checked last week and they said it was a bad 02 sensor. I declined to have it replaced at the time b/c a) they wanted a lot of money and b) the light had gone off. When I fill the tank and start the car, it goes to a very low idle (500 rpm) and acts like it wants to die but then comes back to life and the CEL comes on. After a few minutes, everything evens out and the CEL will stay on but usually the next time I start the car, it turns off again. Again, it seems to be the worst right after I fill the tank.

Apparently this is an issue I can handle myself. I checked the invoice from Honda and instead of saying O2 sensor, it says AF. Is this any indication of the location of the sensor or do I definitely need to go to a store to have the code read? This is a little overwhelming for me because I've never really done anything on my own car before and this seems kind of like a big deal. Thank you.

 

Does the invoice state the trouble code number? If so, post the actual alpha-numeric code.

The air/fuel ratio sensor is located further up the exhaust, whereas the secondary heated oxygen sensor is at the catalytic convertor.

If the invoice doesn't have the trouble code, many parts stores (except California) can scan the trouble code for free. Post the actual number code. Sometimes, the issue may turn out to be something quite different.

 

Thanks. The invoice did not list the code so as soon as I get up tomorrow I'll head to a parts store. I'll post tomorrow hopefully.

 

I ran up to AutoZone and the troubleshooting code is P0171

Fuel system too lean bank 1

It lists several probable causes including large vacuum leak but Honda said it was a bad sensor. Does that code lead anyone to believe that replacing the sensor should help? Is this one under the hood or under the car?

 

The MAF sensor is probably dirty. I've attached a picture of the location too.

For the P0171, check the Mass Air Flow (MAF) sensor first. Honda had a service news article regarding to check it first before spending anytime troubleshoot. CRC make a MAF sensor cleaner, available at most auto parts stores, even Walmart has it.

Leaks at the air intake which can affect the MAF sensor can also trigger the P0171.

 

Thanks. I changed the air filter and cleaned the MAF sensor with the CRC. Today is one of those days where the CEL is off so I don't know if it's worked yet. I'll keep you posted if anything happens.

 

Ok the light was back on today. The engine never sounded like it was about to die with a next to nil idle but that usually only happens on fill up. Based on that PO171 code, do I need to replace the above MAF or is is something else? Is this an easy question to answer based on that code?

 

Go get the code read again to see if it is still the same code or a different code this time.

Was the MAF sensor really dirty when you cleaned it last time?

 

No, to my eyes it honestly looked pretty clean but I know nothing. The air filter and case were filthy though.

 

Going to get the code read again after work. Definitely noticing a drop in gas mileage right now if that leads anywhere else.