U0100 Lost Communication with PCM
P0128 Coolant Thermostat Below Thermostat Regulation Temperature
The u0100 code sets when your vehicle is scanned for trouble codes. It loses communication with the PCM because the diagnostic scanner takes over. The p0128 code is the one of concern. Most likely, the thermostat is not working properly and needs replacing.
Saturday, June 26th, 2010 AT 11:26 AM