This is a guide on how to replace an oxygen sensor using the universal ones that are always cheaper to buy. You have the option to buy one that will just plug and play without splicing, but it's twice as much at about $150.00.

This is a 1994 Civic with a d16z6. And after getting a CEL error 41, I replaced the oxygen sensor and it never came back on since.


Edit: When connecting the wires, if you have a soldering iron, I'd suggest soldering them and using shrink tubing to be sure they don't come undone.
These are the tools you'll need to supply yourself. Adjustable Wrench, Electrical tape, Your oxygen sensor of course (the old one is pictured here, but you should have your new one obviously), an oxygen sensor socket(it has a slot for where your wires can pop through, you'll see in later pictures), a wire cutter and/or wire splitter, and some Anti-Seize(if you ever want to take the sensor out again you need this).


First, remove the harness for the oxygen sensor, the right harness in the picture is securely fastened to a metal bracket, don't try to force that off, cause it's not gonna move.


This is the slot in the oxygen sensor socket I was talking about, put it around the sensor and make sure it is on the bolt.


Now with the adjustable wrench, loosen the sensor, remember, righty-tighty lefty-loosey...I've messed that up a little more than I should have.


After removing the sensor, determine a suitable area to cut, I cut it just after the heat insulator as you can see. Later on I wished I cut it a little closer to the sensor, as you'll see near the end of this DIY.


Now using your wire cutter or wire splitter, remove about 1/2" to 3/8" of the insulation, more is usually better, but don't cut more than an inch.


With the universal oxygen sensor, came an interesting harness, I'm not sure if all universal sensors come with this, but the Bosch one does. This was a little tricky to do because the holes in the yellow stoppers were very narrow, so I had to twist the wires and thread it through.


Now cut excess wire off of the new sensor. I cut about 4" - 5" off leaving what you see here. Do the same and remove 1/2" - 3/4" of the insulation off. Be aware that this insulation is very tough because it is high heat resistant, so a wire splitter is a better choice here. I used a wire cutter and it took me about 10 minutes to get all 4 wires trimmed. When you do this, make sure not to hold the sensor and pull, if you do this, wires can come out of the sensor, and you have fawked it all up.


Now you need to put these wires through the other part of the harness that came with the kit. Before you do this though, make sure you know what wires are connecting to what. There's an instruction booklet that came with it (was too confusing for me to follow) that had a wire connection table. It told you based on what wires your old oxygen sensor had, what each one connects to. So if you had 2 black wires, a white wire and a green wire, which I had, then it told you that the 2 black wires on the old connected to the 2 black ones on the new; the white wire on the old connected to the blue wire on the new and the green wire on the old conencted to the white wire on the new. You'll see what I mean when you get the instruction booklet..I might take a pic of it and post it up if anyone is confused...just ask.

When you did that, now you have to put the yellow stopped on again, but make sure that the narrower end of the stoppe is going to be further from the middle of the harness...so they are pointing outward of the harness.


Then just simply twist them together (it'll be a tight fit) and wrap them with electrical tape. The tape isn't necessary since each wire will be in it's own compartment inside of the harness, but I did it for more assurance that they will not come undone.


Now just push those yellow stoppers all the way down into the compartments. I used a thin allen wrench, but a twig or pencil will do. Then just close up the harness.


Put some of the anti-seize on the threads of the new sensor, and torque it into the hole. You don't need to really tighten it, just use your head and torque it where it's not gonna take a breaker bar to remove. Then make sure to reconnect the other harnesses (I forgot to do this and when the CEL came on again, I thought I did something wrong, but realized it immediately and it worked good)

I didn't want that harness against the motor, so I used some left over wire and just tied it to the AC tube, that's why I wanted more wire from the old oxygen sensor's wires.


IF YOU DON'T HAVE THE CHECK ENGINE LIGHT ON FOR THE OXYGEN SENSOR, SKIP THIS PART.
Remove the ECU fuse, which is in the fusebox in your engine compartment and is a 15A fuse for the 5th gen civics. Remove it for 5 seconds so that the computer's memory forgets about this error, then put it back in. If you don't do this, the CEL will still come on even though it is fixed.

And that's all there is to it. It took me about an hour to do, but half of it was the wire splitting. And also organizing the area for the pictures.

Estimated Time
Newbie: 60-90 minutes
Some knowledge: 30-60 minutes
Mechanically Inclined: 15-45 minutes
This would only be acceptable if you had the correct tools in the beginning.

-Mike

 

Well documented DIY. The only thing I would suggest doing differently is soldering the wires together and using shrink tubing instead of the "twist and pray" method for the wiring.

 

Yea, that is much better of course, but since the connector it came with, makes it difficult for the wires to become untwisted, I opted for the more simple approach...heck, even if you pushed them together, they'd still be in contact with each other.

 

was it difficult unscrewing the o2 sensor out? mines throws an 02 sensor code, but i dont haven't enough muscle to turn it

 

No, it should come out with little force, but you need that o2 sensor socket. If/When you install the new one, make sure that you put anti-seize on it