DTC P0126:00, P0128:00: Notes

DTC P0126:00, P0128:00 (LF, L5) DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0126:00	Thermostat stuck open
DTC P0128:00	Thermostat stuck open
DETECTION CONDITION	P0126:00 The PCM monitors detects based on following calculation with ECT sensor No. 2 and estimated ECT sensor No. 2* at judge timing. When the difference between ECT sensor No. 2 and the estimated ECT sensor No. 2 is at the set value or more, a malfunction is detected. *: Estimated ECT sensor No. 2 output value when it is determined that there is a thermostat-open malfunction. MONITORING CONDITIONS IAT: above -10 °C {14 °F} Vehicle speed: over 40 km/h {25 mph} Absolute load: above 14% P0128:00 The PCM monitors MAF, IAT, VSS and ECT signals and calculate radiator's heat radiation ratio while following monitoring conditions are met. If calculated value exceeds specification, the PCM determines that the thermostat is stuck open. MONITORING CONDITIONS IAT: above -10 °C {14 °F} ECT at engine start: below 52 °C {126 °F} Vehicle speed: over 40 km/h {25 mph} Diagnostic support note This is an intermittent monitor (engine cooling system). The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2)/Snapshot data is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	Thermostat malfunction ECT sensor malfunction Cooling system malfunction PCM malfunction