I have a 95 Civic CX with a d15b7 engine. I bought it as is about two weeks ago and the CEL was on already. I pulled the code and it was code 41 (primary oxygen sensor heater). Now, I've read many of places that this could be fixed by these three things:

1) Replacement of the O2 sensor
2) Replace the ECU (i really don't want this to be it)
3) Replace fuse 15 (not too sure about this one)

Now, no, I have not replaced the O2 sensor to test that theory out. I'm trying to get all information before I start just buying parts. All threads I've read have all had Code 41, but no pulsing idle. At first I thought that it would be my TPS, along with many others thinking that also. I took my TB off and switched it for a different one I had lying around the garage, which also came off of my last d15b7. Still pulsed at idle. I could be going down the street with it out of gear, and it would still pulse. It won't pulse ALL the time, but does the majority of the time. Any suggestions would be great.

 

This is almost always simply you need to replace the oxygen sensor. To confirm that this will fix the pulsating idle, unplug the oxygen sensor connector and see if the pulsating goes away. If not, it's probably a vacuum leak.

 

I have unplugged the IACV, and the idle balanced out. As far as the code 15, the fuses are good so I'm thinking the o2 sensor. Will replace it and hope.

 

If your idle really balanced out after unplugging the iacv then you clearly do have a vacuum leak.

 

Fixed the idle problem. Sprayed brake cleaner into the intake manifold where the IACV is and cleared it. Haven't replaced the O2 sensor however. Gotta replace my master cylinder first. Leaking by the brake booster. Just gonna start my rear disc conversion.

 

Thanks for this thread! I got code 41 and 14, so I'll remove the IACV then clean it and hopefully this will fix the issue.