Detection Condition

DTC P0126:  If ECT signal never exceeds 160°F (71°C) after engine start for specified period, PCM determines that coolant thermostat is stuck open.

Monitoring Conditions:

• Difference between ECT at engine start and minimum IAT: Less than 43°F (6°C)
• IAT: More than 14°F (-10°C)
• Vehicle speed: More than 5.9 MPH

DTC P0128:  PCM monitors MAF, IAT, VSS and EAT signals and calculate radiator's heat radiation ratio while following monitoring conditions are met. If calculated value exceeds threshold, PCM determines that coolant thermostat is stuck open.

Monitoring Conditions:

• Difference between ECT at engine start and minimum IAT: Less than 43°F (6°C)
• ECT at engine start: Less than 97°F (36°C)
• IAT: More than 14°F (-10°C)
• Vehicle speed: More than 5.9 MPH

This is a continuous monitor (THERMOSTAT). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for same malfunction has been stored in PCM. PENDING CODE is available if PCM detects malfunction condition during first drive cycle. FREEZE FRAME DATA is available. DTC is stored in PCM memory.