Generic
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

GM
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    ECT Below Thermostat Regulating Temperature Conditions
Cause:
    Engine running, ECT and IAT inputs from 14-97°F, then the PCM detected the engine coolant temperature did not reach at least 167°F with the Water Temperature Counter Diagnostic running.

Nissan
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Engine coolant temperature - too low
Cause:
    Thermostat, ECT sensor, cooling system, ECM