2001 accord ex 4 cylinder p1259 vtec malfunction after engine change

i just replaced an engine in a 2001 accord ex with the 2.3 4 cylinder vtech f23a1. After getting the engine installed and running, i noted the radiator cooling fan running with the engine cold and an immediate check engine light with p1259 code. I cleared the light with engine off key on and it immediately returned. I also noted the cooling fan on as soon as ignition was on. I read on another forum about the vtec oil pressure sensor plug being swapped with the water outlet temp b plug. I checked and the water outlet sensor had two plastic prongs that only allowed one of the two plugs to fit. After checking the old motor, i found the water outlet sensor was the same except it didn't have the two plastic prongs. I swapped out the water sensors and swapped the plugs so the green plastic end was on the vtec solenoid and now all is good. I just wanted to post this as I'm sure someone will run into the same problem and hopefully this will help.

Interesting, thanks. Good thing you found a possible answer somewhere...little crap like that can drive you bonkers if you have to whittle down to the cause...

Thanks dude. That helped a ton. Couldnt find anything for weeks on my problem, then found your post.