Hi guys,

To pass emissions test, I was told that I need to replace the primary as well as secondary oxygen sensors. It's about $130 for the parts and would be $170 for labor. I have read various places that replacing these isn't very difficult. Does anyone know of a good thread that explains how to replace these?

It's for a 2004 Civic EX.

THanks

 

It's really easy, but you have to have a special o2 sensor socket (commercially available). You might also have to use some PB blaster or other penetrating spray because the o2 sensors do seize over time.

It's really simple. You use the socket and a ratchet (or maybe a breaker bar?) to remove the o2 sensor, then you unplug it. Installation of the new one is reverse of removal.

The primary one is easy to get to. The secondary one must be accessed from under the car.

 

where are they located?

 

and this special 02 sensor socket. is it relatively cheap (under $10)?

 

It relatively cheap bought mine long ago, maybe $10-$15, it just a deep socket with cut slot on the side the the wire. Maybe you can use a regular cresent wrench.

 

On my SI I had a heck of a time getting the old ones off. There was no easy way to get to the secondary and apply the amount of force needed to break it loose. So I actually had to remove the cat converter. PB blaster did nothing. Applied heat for 20 seconds and hit it with my impact and it finally busted loose.

Your primary may be in an easier location than the SI's but, I had to remove the A-pipe to again get enough leverage on it.

BTW, the NTK replacements I thought would be a good OEM replacement choice failed within a year. Put on Bosches and things have been good for over a year now. and yes I know everyone says bosch sucks on hondas...but...