ok guys i have searched and searched about this but knowing yall in two seconds you will have the answer; i have a 93 cx hatch with a b16a2 in it. its throwing a code 41 and i replaced the o2 sensor but i dont think i replaced the correct one, i think the engine has an aftermarket header w/out a bung so im not sure what to do. the o2 sensor is just in front of the cat. is that considered the "cat o2 sensor" even when it is not directly on the cat. ( sorry for being dense but i have to be sure)
My question is, does this engine have two o2 sensors? and where would i expect to find the connector? the o2 sensor by the cat is a 4 wire.
thanks for the help and sorry for what im sure is a repost.

 

All 92-00 Civics should have an O2 sensor before the cat, and after the cat.

On a B-series manifold, the front (primary) O2 should be in the manifold, directly before the cat.

On most cars (or at least on all of my Hondas) the rear O2 (secondary) should be IN the cat. Like, going into the middle of it. Not 100% sure, because both of my Hondas are 99 or newer.

Code 41 should refer to the primary, or the one that comes before the cat. If you are somehow missing that sensor, your car will not run well at all. As far as actually diagnosing your code 41, I can't really tell you; I've never dealt with an O2 on an OBD1 Civic.

 

https://honda-tech.com/forums/hybrid-engine-swaps-18/%5Bfaq%5D-%22my-vtec-doesnt-work%22-1812135/

Halfway down is code 41 troubleshooting. Your civic only has one O2 (92-95 only have one before the cat). Just needs to be before the cat on the pipe.

 

ok guys i followed the troubleshooting again ( i found it last night, hoping this was a different one) and i encounter the same problem, i get to page 11-49 and get to the pinout and my ecu only has three plugs aswell it is a blank slot at A-23. any help would be great, again. i didnt do the swap but it has a p30 in the car. im going to try and run a straight wire from the o2 to the ecu. im looking for a p30 pinout diagram to find which wires to run
thanks

 

a23 is blank? thats highly unlikely, are you sure you are counting the ecu pin correctly? looking at plug a of the ecu it should be on the top row, second from the right.

continue to troubleshoot, dont run new wires

 

The CX hatch has a one wire 02 sensor from my knowledge if you are using the CX engine harness then it may not be compatable for the four wire 02 sensor you would need a vtec harness with four wire 02 sensor and you shouldnt have a code, you could replace ten primary o2 sensors and still get a code, I have a 97 hx it came with a 7 wire wide band 02 i have a b18c swap in it which requires a four wire not a seven wire. I had to change the engine harness out because i was throwing the same code 41 you were i put a bosch universao o2 sensor in switched the engine harness out and vwalaahhhh!! no check engine light. Good luck!

p.s. If your computer is OBD1 92-95 then you only need one o2 sensor if it is 96 and up you need two o2 sensors, you should be obd1.