I'm dealing with a '96 Civic right now, belongs to my mother actually. It was throwing code P0715, along with shifting hard enough to chirp the tires going into second at half throttle, also wouldn't kick down into passing gear at the end of it. So I went through flowchart in the factory service manual. everything checked out, replaced the mainshaft speed sensor anyway due to a screw up when measuring for ohms. Issue remained. So I put in a good used automatic, kept the original torque converter but drained the old fluid out of it. Put everything back together, filled with genuine Honda Z1 fluid. Shifts smooth like it should, everything seems fine for a month or more and the the CEL comes on, P0715 again. Check the wiring plug on sensor seemed a little loose, made sure it was tight, reset ECU. Went for at least 2 weeks maybe longer before it through the code again. I've reset it a a few times now, last couple of times it came back on within a week. I've noticed that sometimes it seems to shift a little harsh (nothing like the first trans though) especially at light throttle. At WOT it seems to shift fine. Also noticed when you come to a stop it idles super low, it actually stalled on me once. Any thoughts? I'm thinking the torque converter is bad, but i'm looking for opinions before I try another one. Sorry for the novel

 

You may want to measure the resistance of the mainshaft speed sensor in the new transmission and test it for short. If it's fine, do you have a known good ECU to swap in?

 

Already checked for open, short to ground and short between both wires, everything is good. mainshaft speed sensor is actually brand new OEM honda. I have checked the resistance though just make sure it wasn't DOA.

Unfortunately no. But I can probably pick one up somewhere. I thought about the ECU, even pulled the cover to see if anything looked funky, but I don't think thats it. I'll probably try another first though seeing as how they're cheap and a whole lot easier to changed than a torque converter.

 

Yeah, I hope it's the ECU so you don't have to pull the tranny again. Good luck.

 

Ok, update. The CEL went out on its own this time. I haven't checked the code reader yet to see if all the readiness monitors are set. But i'm confused.

 

Let's hope the code never returns! You accumulated so much good Karma through all your car help here that the car cured itself.

 

Haha, I wish. I finally scanned it today, its still storing codes P0700 and P0715. No CEL at this time though (CEL bulb still works in case anyone wonders)