Swapped a B16a into a 91 CRX HF; OBD0 PR3 ECU Anyway, I'm getting code 6 from the ECU (Defective Coolant temp circuit/sensor), and I can't figure out why. The sensor is plugged in, I've tried swapping the sensor (and tested the resistance of both sensors, they were the same), and I traced the connector pins back to ECU/ground. The car runs okay but is obviously in limp mode (bad idle, 7200rpm rev limit, no VTEC etc). If I use the old HF ECU (PM8) it does NOT throw the code and runs much better (indicating that it is reading the ECT correctly). I've searched around to see if maybe on some of the PR3's the coolant temp sensor came in on a different pin, but that doesn't seem to be the case. Why else would this happen? Bad ECU? ECU code is 37820-PR3-003, is 003 some weird revision or something? I opened the ECU up and nothing appears to be damaged/modified.