Lissav

This has been a bad week for both of my cars...need some help.

So the oxygen sensor went on my '00 civic. The CEL is Code 1, which is 1 O2A - Oxygen sensor #1 , which i've always assumed/thought was the first o2 sensor, the one that's before the cat. Fair enough (correct me if i am wrong).

I went to parts source and got a NGK oxygen sensor for my car.

When i went home to change it, i pulled the stock one off and compared it to the one i bought. Everything was the same except the plug, the one i bought had the reverse plug. It had the plug that's the same as the plug on the engine harness that i connect my OEM o2 sensor to. It's funny because because it had a reverse plug i could connect both o2's to each other.

Anyway, i cut the plug off my stock one and wired it up to the new o2 sensor and put it on. Started the car, after 2 mins the CEL came back on, checked it, again code expletiveing 1.

I took the sensor off again today, checked the wiring and all my work, everything looks perfect, so wtf.

The only things i can come up with:

1. I am changing the wrong o2 sensor, but there is no way as Code one is your number 1 sensor which is in fact the one before the catalytic.

2. On a 4 wire o2 sensor, there are 2 black wires, they are both heater wires, i don't think it matters which is connected to which as they do the same thing. Right/wrong?

3. The o2 is broken, but how can i possibly check that?

I plan on swithing my o2 sensors and bringing the cat one to the front and ngk to the back and see if the code changes. Are the plugs for them identical?

lv6l

If the harness does not match up, it is not intend for that bank. Normally a good scanner can tell you which bank and which sensor it is. You can also drop by a local mechanic shop or a smog center and have their professional scanner scan your car. It will give detail information. From there you can either determined which sensor it is OR you can take that information to a Honda dealer and they can help you get the right parts. Always buy o2 sensors from the dealership because when you are messing with smog it's best to spend a bit more but do it the right way the first time around. Good luck.

obuhmyuh

when i google imaged o2 sensor #1 all the pictures show the 02 sensor below the car (not off the header) so it sounds like you bought the right one. my guess would be the wiring.

lv6l

Where did you buy your NGK o2 sensor?

dude_123

How did you joined the connection of the new O2 with the OEM plug? was it crimped connectors or twist it together and tape it? Well if they are there is your problem.

Don't mix upstream and downstream O2, its a big no, no. There are a few ways to test out the O2 sensors as well. Use a multimeter and probe the O2 signal wire with (+) lead and ground the (-) lead on ground source. Then set the multimeter to the lowest V reading, 2v or lower since O2 doesn't go above 1V.

Turn on the engine and let it warm up and let it go into closed loop. The reading should be around 450mV, snap WOT and it should change to 650mv~800mV, if the reading moves slowly that sensor is bad/soon to be.

If you have the sensor on the table you can use those hand held propane torch to test it too. Probe the sensor the same as above and set it to the lowest V reading on the multimeter. Turn on the propane and lite it, burn the tip of the sensor, when the sensor is at operating temp you should get readings in mV. Again look at the readings. Slow or no reading = bad, responsive reading = good. Hope this helps.

But if you have access to a good scan tool that have graph features these test are not necessary.

obuhmyuh

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dude_123 &raquo;</TD></TR><TR><TD CLASS="quote">How did you joined the connection of the new O2 with the OEM plug? was it crimped connectors or twist it together and tape it? Well if they are there is your problem.

Don't mix upstream and downstream O2, its a big no, no. There are a few ways to test out the O2 sensors as well. Use a multimeter and probe the O2 signal wire with (+) lead and ground the (-) lead on ground source. Then set the multimeter to the lowest V reading, 2v or lower since O2 doesn't go above 1V.

Turn on the engine and let it warm up and let it go into closed loop. The reading should be around 450mV, snap WOT and it should change to 650mv~800mV, if the reading moves slowly that sensor is bad/soon to be.

If you have the sensor on the table you can use those hand held propane torch to test it too. Probe the sensor the same as above and set it to the lowest V reading on the multimeter. Turn on the propane and lite it, burn the tip of the sensor, when the sensor is at operating temp you should get readings in mV. Again look at the readings. Slow or no reading = bad, responsive reading = good. Hope this helps.

But if you have access to a good scan tool that have graph features these test are not necessary. </TD></TR></TABLE>

very good input i would say... try all of this and keep us up to date

quicksilver1689

which code was it exactly? first 02 sensor? 2nd was wasnt tripping any codes? if so you know the cat is good or the computer doesnt see it as a problem, yeah the guys here gave u some good info, a scanner really can tell you alot about the operating parameters of the motor. I havent really used a scanner on alot of Map cars, Will it display long term fuel trim?

lv6l

A good scanner will say something like "code 01 - bank 1 sensor 1" you then take this to Honda dealer ship and ask an older more experience worker and he would be able to tell you and give you the right correct part or at least help you with your current situation.

HondaPartsHero

you may have gotten an Accord O2 the plugs are reversed from the civic/integras plug orientation.

92bubble

also when i replace o2 sensors at work i <U>always</U> try to stay away from the ones that you splice yourself. if they are not joined perfectly there will be a higher amount of resistance through the wires which will in turn alter the signal going to the computer, thus making it run bad even though it should be running fine.