Bruce Lee

I just got the code P0131. On a 1999 Honda Civic.
I know it has to do with the O2 sdensor. I'm not sure where this sensor is located. I know there are 2 of em.
Manual says closest to the cylinder head b4 the cat converter.
Where exactly is this located?
i reset the ecu, drive it like maybe 4 to 5 miles then the cel comes up, and the transmission act funny. therpm revs up the car won't move then it just kicks in and takes off, is that something like the limp mode?
Any tricks or anything I can do about this?
By the way this cil came on 1 day after I changed the oil. I had a hard time with the oil filter, etc. there is something going into the engine block right above the oil filter, is that maybe a o2 sensor?

tech8

Bank 1, sensor 1 is the pre-cat O2 sensor.




If you need an O2 sensor, sparkplugs.com has them for a good price. 10% discount code <U>srto2</U> on Denso or NGK O2.

tech8

The above image is for an EX.

If your's is an LX, it looks to be in the Exhaust Manifold:



It also seems like there is a difference in part numbers for automatic or manual transmission.

Bruce Lee

So #8 on that diagram is the one I'm getting code P0131?

tech8

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bruce Lee &raquo;</TD></TR><TR><TD CLASS="quote">So #8 on that diagram is the one I'm getting code P0131?</TD></TR></TABLE>

Yes.

Bruce Lee

I see, thank you. today i went working on it again. rest the ecu, run the engine for a while, like maybe after 2 minutes the light comes back on.

I took the connector off the sensoe and got a different code all toget ther, i think it was 65 or something which didn't help much. Do you think changing my oil had anything to do with the light coming on?

Bruce Lee

Also do you think this would affect the tranny, I mean when I drive sometimes with the light on, the rpm goes up the car doesnt want to move.

Bruce Lee

On sparkplug.com, it says rear and front. Which one would be the one for #8 on the diagram for the exhaust Manifold location?

tech8

You want the front O2 sensor. Changing your oil would not cause the O2 sensor to come on, probably a coincidence.

The O2 sensor will cause the ECU to change its air/fuel mixture. With a bad O2 you may have a little poorer performance, poorer gas milage, and higher emissions. It should have no effect on the tranny.

Bruce Lee

you think I need to replace both sensors or the one showing on the cel si the bad one?

Vsm Hatch

if you try to order the front one and the rear one on sparkplugs.com the part number that shows up is the same. So I'm guessing the before cat and after cat o2 sensors are the same. Sounds logical since the before cat o2 sensor is for closed loop adjusting fuel for optimum emisssions. The after cat o2 functions as a diagnostics to compare with the before cat to see if the cat is good or bad. Its supposed to make it easier for the smog/repair guys to find out if the O2 sensor is bad or the cat is bad or if its some other problems, but it cause more problems than it fixxes. Sucks for us obd2 guys.

SkyliteCustomz

if my bank 1 o2 sensor is bad..i'll just switch it with the bank 2 o2 sensor. PROBLEM SOLVED lol

Bruce Lee

Yea man tell me about it, infact one would be enough, they just make things difficult. i was gona switch the connector for the 2, then i said lem me skip that little experiment, might get more cel's etc, and mess it up even more.

Bruce Lee

you know, lol.....haha that's something to give a try.

SkyliteCustomz

haha give it a try and let me know how it turns out

Bruce Lee

By the way , what's the socket size to have this removed? any ideas?

tech8

It's 22 mm (metric) or 7/8" (standard). Usually you use a special O2 sensor socket ($10), which has a slit in to to allow the wire to slide through.

If you remove the cover (#3), you may possibly be able to use a box end wrench on it.

The O2 sensor may be very tight, so you may need to use a breaker bar, or pipe (cheater bar).

Search google to get an idea what you are up against. If it is too tight, you may want to just have a mechanic do it. You don't want to round off the sensor or strip the thread in the O2 bung hole, which will be more $ and work.

Bruce Lee

Hey there.

Thanks for the info. I think I'm a buy the part, then have a pro deal with opening it, etc. Don't want it to break and spend more $$.