My buddy has a 1997 Civic HX, with the D16Y5 and manual transmission. He's had a check engine light for P1164 since he got it, and has to be able to pass emissions to get it tagged and on the road legally. He replaced the top O2 sensor, and reset the CEL. Drove about 49 miles before it came on. He said he can reset it, and then it will always come back on (presumably before the readiness codes are reset).

I've been doing some reading, and saw that the A32 ECU (stock in '97 HX Civics) sometimes can be faulty and cause the P1164 code? I was thinking of going to a junkyard and trying to find a used A33 ECU and throw that in.. would it be just plug-and-play?

According to this post: https://honda-tech.com/honda-civic-d...pd-hx-1475099/
we would need to look for a '99-'00 Civic (manual trans).

Would this be the next logical step to take, or are there other things we should do to rule out the top O2 sensor before going down that route?

 

The next logical step would be to attack all of those wires with a voltmeter to make sure they aren't damaged, and to visually inspect them for fraying or damage.

 

They visually look good.. it looks like a 5-wire plug (if I remember correctly), but it does NOT look like the OEM plug because it's connected by butt-connectors. Should I just verify continuity between where I can probe (probably the butt connector end) to the factory harness plug?

 

Visually does not confirm anything, you need to use a multimeter. Also if there are butt connectors than thats worst.