Ok so I have a '95 civic ex with B16A1 motor swap. I've been looking thru so many forms and its a fight between the O2 sensors on how many it has. 1 or 2. I want to know what is the number because I have an O2 sensor at the end of my headers before it connects to the Cat. and before I replaced the Cat. because it went bad I saw that I had an O2 sensor on it but the wire was cut off from it so I have no idea where its wired to on the wire harness.
Reason why I ask is because I'm getting new headers and I need to know if the B16A1 motors have 1 or 2 sensors.
(Car starts up rough in the mornings and dies if I Dont rev the engine a couple of times. But starts fine when I turn it on after words and if I haven't started it up all day but do so in the after noon it also starts up fine)

 

https://en.wikipedia.org/wiki/Honda_B_engine#B16A1

The B16A1 engine is OBD0 and the stock version of your Civic is OBD1, so neither would use a secondary O2 sensor. What ECU is running the engine in your Civic?

 

It's OBD1 I'm running on

 

Needs only one O2 sensor (primary).

 

Thanks man! Been confused with a lot of forms saying it's 2 and some say its one.

 

Obd0 had 2 unheated inthe manifold
Obd1 one in down pipe
Obd2 one in pipe one in cat

Just use what your ecu requires

 

This is very important. It is ECU dependent, not motor.

 

Woah, what about jdm? Not the same emission standards. Couldn't a jdm obd2 only require one? My B18C only has one.

 

B16A1 motors are EDM/UKDM. And I have an OBD1 with one O2 sensor.

 

Emissions standards are ecu dependent, like I said before you use what your ecu requires....

 

JDM OBD2A uses only one oxygen sensor. Not sure about OBD2B (1999+). But JDM OBD2A is really more like an updated OBDI than it is like USDM OBDII.

 

Keep it simple. It purely depends on what ECU you're running. OP already stated he has an OBD1 ECU so it will be one primary heated sensor behind the block after the final merge in the collector weather it's JDM or USDM.

 

This is correct