ok i know this has been covered from many diff areas but i havent found anything like this. i have recently put an obd 1 h22 in a 94 accord lx. everything is fine except something is screwy with the ECT sensor. when hooked to the scanner the temp says 246 always even when the car is stone cold. as you can imagine this makes the cold start bad. it runs rough until it warms up. i cannot figure out why its stuck at 246. i tried new sensors, bled the cooling system and checked all of my wiring. everything is ok. there is also no check engine light either. i read the voltage from the IAT and ECT sensors on the scanner should match but they dont. the IAT is 3.08 volts which is in spec but the ECT is .08 volts meaning it thinks its hot. if anyone can help it would be great ive been searching all day. thanks oh yeah the gauge is working properly too.

 

I'd say you're missing a ground.. Usually when the PCM sees the ECT voltage sit at 0v or 5v, it'll show that the ECT reads either -40 or 240 degrees..

I can't remember, but I believe that if it reads high (240) the ECT has a poor ground.

Good Luck..