I got the heat shield off the header and moved out of the way but I have no idea how to get the sensor out. The biggest wrench I have is 19mm and its bigger than that, also the angle it's at the wrench has a hard time fitting because of all the AC components. I would try a socket but the connector and wires are in the way. How the heck do I remove it? I sure hope the one in the cat is easier to remove.

 

Some PB blaster and a breaker bar will help. Go to your local auto parts store and buy a special O2 sensor socket like this one:

 

ahh gotcha, yah i've been spraying the PB blaster and I got a wrench to turn it a little bit but its not close. I wonder if I can rent it from autozone.

 

A breaker bar will give you more torque. Definitely ask AutoZone about a rental because the socket costs $10-$15 to buy.

 

Advanced Auto sells them for about $10 and they have them for rent also.

 

I got the one in the header out which is the primary I believe. I tried a quick cleaning with a wire brush and cleaner. Dried it and put it back in, reset the ECU and the CEL came back on. Kinda figured that would be the case. How can I tell which sensor is bad? I doubt my "cleaning" actually cleaned it to work if that was the one that was bad. Also are the sensors the same for all Honda OBD2 motors? Reason I ask is I am looking to swap a B18c type R in and thats OBD2. I would hate to have bought new ones for the D16 when it isnt staying in and then they cant be used for the new motor.

 

The CEL codes are different for the primary versus secondary O2 sensors. What CEL codes are being thrown?

 

Thats what I figured because I thought the primary is for the A/F ratio and the secondary is just a cat efficiency or something. I wish I had my own scanner or w/e, Autozone just told me its my O2 sensors and I asked which one and they said you should replace them both. I'll have to go back and get a different guy to do it.

 

You don't need a scanner. Reconnect all sensors, clear the codes from the ECU, run the engine, and then pull the codes at home as described here.

 

wow amazing, 1 flash and i assume its the short 1. so the 1st or primary oxygen sensor is bad. that is quite the trick

 

So now you can focus entirely on the O2 sensor before the cat.