Hi.
I have a 1995 Honda Civic LX, with about 120, 000 miles on it.
I was experiencing somewhat lower gas mileage and some loss of power (especially on hills) for a while, when my 'Check Engine' light came on and stayed on about 1-2000 miles ago. Checked code, and it pointed to the Oxygen Sensor as the problem.
I bought an 'Universal' Oxygen Sensor off of Ebay and installed.
Have had in for about 500 miles now, and this is what I observed since installation:
1) When I installed the new part, I had 2 black, 1 white and 1 green wire on old part, and end of the sensor (about 1" long) had several holes (about 10?).
New part had 2 black, 1 white and 1 BLUE wire, and only 2 holes at the end.
I attached the green wire to the blue wire (had to splice the wires), and installed the new sensor. Question 1 - are either of these items a problem?
2) After installation, I thought I would have to disconnect the battery to reset the computer system, but did not have to do! When I started up the car, the light was off!
3) The first night I drove the car, no problem with light coming on...... but the next morning, after about 10 minutes of car warming up, the light came on. I have since then observed that light comes on every time car sits long enough for engine to be cold, and then will come on after about 10 minutes of car warming up! All I have to do is to turn engine off and light goes away, and does not come back on again, until I let car get cold again!
What could be the problem?? Note that I have noticed better power on hills now, but have not seen any improvement in gas mileage, maybe even less!
Thx.
Bob

txgreasemonkey

I am not a fan of universal oxygen sensors or those made by Bosch. I would recommend installing a Denso in your Civic. Over time, you want the best sensor or you will pay for it in poor gas mileage and performance. Oxygen sensors are EXTREMELY sensitive to anything, particularly silicone spray, WD-40, or any oil on the pigtail connector. Don't even use non-chlorinating brake cleaner or electrical contact cleaner. NEVER use any of these products around the oxygen sensor or pigtail connector. If you do, the ECM will keep throwing a code forever.

Until your Civic warms up, it's running in what's called "open loop" or pre-programmed mode. What matters is after the vehicle warms up and the oxygen sensor is adjusting to the constantly changing conditions. Remove the pigtail connector and gently dress the male and female connectors with jeweler files.

Bob6831

So, you believe that filing (cleaning) the connector pins will stop the sensor from coming on when engine is cold????

txgreasemonkey

Yes, I think it's a distinct possibility. Another possibility is that the new oxygen sensor was contaminated from PB Blaster or brake cleaner residue on the female threads. It's best to give plenty of time for everything to air out.

Bob6831

So, what about the first part of my question.... was connecting Green wire to the Blue wire correct? And does the number of holes in the sleeve at the tip make any difference?
Thx.
Bob

txgreasemonkey

Sounds like you hooked it up right to me. Normally these universal sensors come with decent instructions, but it doesn't appear there's any other way, to me. I'm not an expert on these matters but the no. of holes could make a difference. This is how fresh air is drawn into the sensor for comparison. My guess is that it does.

Bob6831

Thx, grease, but does anyone else have any thoughts on whether I installed the wrong part, as far as not having same # of holes in tip sleeve?
Also, I was surprised that didn't have to disconnect the battery to reset the computer, ie. to turn the Check Engine light off. The material I read said that I would have to do that!
Thx.
Bob