Has anyone replaced an O2 sensor in a 99 honda civic ex. Needing to replace the one before the catalytic converter, wondering how difficult of a job that is? Probably going to going to go with the universal 4 wire, it is a lot cheaper than the one for it.

 

I just replaced my O2 sensor on a 96 Civic. I don't know how much different it is for a 99. It wasn't too difficult, but definitely need patience. I purchased the new one from the local automotive store and also "rented" the socket set, too. You will definitely need the socket set. Their policy is you pay for it when you "rent" it (about $30) and then when you bring it back, you get your money back. I used an OEM version and it cost about $80. Your car will still run if the O2 sensor is bad, but the engine light will remain on and then you chance something else happening and not knowing. It's worth the investment.

 

Are both of my 02 sensors shot!? My engine starts really high like 3000 rpms then the CEL comes on and it revs between 500rpms and 1500rpms maybe even like 2000 rpms. I know its not a vacum leak becuase I have just replaced all gaskets and vacum/coolant lines on the engines head

 

Maybe replacing the coolant lines let air in, which is causing your Fast Idle Thermo Valve to act up. Not sure if that would actually cause it to rev to 3k on start up though:shrug: Follow the directions in your manual (owners or service) for coolant replacement, to get any air out.

As for replacing O2 sensors, that's one of the few things on a car that I'd recommend using a little anti-seize lube on. Some will recommend it on the packaging or even have it included.

 

What code is your CEL showing?

 

P0420... either a bad 02 sensor or a clogged cat converter... was told that it was more than likely a bad O2 sensor with that code.

 

Not very likely. P0420 codes on a honda are almost always caused by a worn out cat.

 

Blackhatch: I did a timing belt water pump on a acura integra and had the same problem where the car had a high idle and a searching idle. I called my buddy that used to work at honda and he said it almost always happens when you drain the coolant. Reason being is the two cooling hoses going to the idle air controler empty out and fill with air, causing it to go on high idle and full rich mode. All you have to do is run the car for a while till it gets hot and open the bleeder to get the air out. Just make sure you get the system filled up all the way. The code is must likely related to the way it's running, so don't replacing o2 sensors or cats just yet.

 

thanks for the help...