Engine Controls - PCM Software Can Cause DTC P0128/P1486

SOURCE:
Honda Service News October 2003

TITLE:
PCM Software Can Cause DTC P0128 or P1486

APPLIES TO:
2001 Accord or 2001-02 Civic

SERVICE TIP:
If you're troubleshooting DTC P0128 (cooling system malfunction) or DTC P1486 (cooling system malfunction) set, here's something to keep in mind: The problem may not be the coolant thermostat, but a deficiency in the ECM/PCM software. Under certain driving conditions after a cold start, the ECM/PCM can miscalculate how fast the engine coolant temperature rises and set DTC P0128 or P1486.

If the heater and temperature gauge work OK, don't replace the thermostat for this DTC; it doesn't give a lasting repair. Instead, do this: For 2001 Accords, replace the ECM/PCM (see S/B 01-064, MIL Comes On With DTC 0128); for 2001-02 Civics, update the ECM/PCM software (see DTC P0128).