zeroptzero

I've got a new primary O2 sensor on the way for the stock header to replace on my MYO2. I had a quick look under the car today and it looks like a major PIA to access. Has anyone done this before ?, anyone have some tips on how to replace this thing efficiently ?. I was hoping to avoid removing the header if at all possible, but it's a super tight fit in there. I've got a proper 02 sensor socket , but it looks like a very tight space to access. Any advice would be appreciated. I tried a search but nothing came up. thanks for any replies.

MasterForce

i did mine when i did an oil change took me like 10 minutes. heres a quick run down.

Make sure your lift up the car and the car is COLD!!! i did mine while it was still kinda hot and i only drove 5 minutes! If you do this while its hot get some rags AND WATCH WHERE YOU PUT YOUR HANDS AND ARMS because some things will be hot. If you have a car on a lift its 99.99% more easier!!! First get a wrench to unscrew it. I think it was a 14 or 16 but i forgot. Then it will be loose. You will need to unscrew it with your hand because of the wire thats attached to it. Since you said you didnt need the old O2 sensor then you can just cut the cable. Use the rags when you are unscrewing it by hand since it will prolly still be hot (if you drove the car). After that you will need to detach the connector at the end of the wire. This is kinda on top of end of the transmission. If you follow the wire you will know which one to disconnect. Theres a tab on top which you push and and pull so you can take it out. Once you get that out you can either take the clips that hold the wire in place or leave them there. I personally yanked the wire and cut it since i didnt need it anymore. Once i took all the wire out i screwed in the new O2 sensor. First by hand then by wrench. Make sure you dont connect the wire yet so when you are screwing the O2 sensor you can twist the wire to so it wont rip. Then after its in just make the wire a trail into the connector on top. Make sure to secure the wire. after that then your done! This might seems like it takes 1 hour but once your under the car its easy.

zeroptzero

thanks very much for the write up, that relieves some of my concern. I never thought about cutting the old one, that'll make it easier for sure. I won't have it on a lift, right now it's on jackstands.

So you got it off using a box end wrench ?, if that's the case I'll try to use one , it might be easier to fit in the space as compared to my 02 sensor socket. Thanks for the quick reply, much appreciated.

AMS MIKE

you need a 22mm wrench to remove the O2 sensor

why cut the wires???? you have to unplug the clip anyway.... just unclip the plug first, then when you unscrew the O2, it doesnt get tangled.

its very easy!!!!

when installing the new sensor, put a dab of anti-seize on the threads (do not get any on the sensor itself)

zeroptzero

ah okay, so you would use a 22mm box end wrench to remove it ?, that will fit in the available space. I hear ya on the cutting of the wire, I guess you could do it either way , probably just the same to pull the wire first. thanks for the reply.

marcucci

I definitely wouldn't cut the wires unless you opt for the cheaper splice-it-yourself solution vs the direct-fit type (that's 3x the cost). I personally stay away from the splice type, they usually work and last fine but for the infrequency with which O2 sensors go out... it's usually not worth the extra time to splice.

Also, O2 sensors usually die for a reason. Exposure to water on the backside, an excessive rich environment, or exposure to water on the sensor side. If yours died at <100k mi I'd think hard about what may have killed it, so you don't kill another. They do fail randomly on their own, but in general... not ever before 100k. I've had Honda sensors last >250k mi and in general, don't see failures before 150k.

zeroptzero

thanks for the reply, my original one hasn't shown signs of failure yet (55k miles currently), but I can get a used one with only 3k miles on it right now. My car was borderline on the last emmissions test for hydrocarbons (unburnt fuel), so I thought it might be a good idea to try a new O2 sensor if I can do the work myself, it's worth a try. An excessively rich air fuel might be on cause, not totally sure though. I don't really care about the cost , if it doesn' work then at least I have a fairly new sensor in the car for the future.

MasterForce

well i cut mine because i didnt need it no more. my o2 sensor went bad and i was getting a CEL. so i got a used one. if you arent gonna use the one thats useless why not try to get it the fastest way out? the trash aint gonna care if you cut the wire or not. i didnt even take out the clips. i just tied it with zip ties. who cares about it anyway. its not like people are gonna know...

zeroptzero

well I got mine off with the open side of a 22mm box end wrench, thank god those wrenches are pretty long in size as it gave me enough torque to crack it loose, those sensors are on there pretty tight after 7 years. The Releaseall lubricant may have helped as well. I think a properly sized crows foot wrench would have worked as well. I used an 02 sensor socket on the secondary sensor with ease, but there is no room to use one on primary.

Now I just have to figure out how to remove those darn Honda clips that they use to strap the 02 sensor wire.

Thanks for all of the replies, they helped me enormously.

marcucci

Honda wire retainer clips come off easily with needlenose pliers, you have to pinch them on the backside. Unfortunately the ones on the O2 sensor are so wound up on top of the trans that you usually have to bend the metal tabs slightly and use a super-long flathead to compress them. IIRC the shop manual procedure is to remove the bolts that hold the metal tabs on and take them off that way.