DTC P0126-00; Thermostat Stuck Open: Notes

NOTE:

To determine the malfunctioning part, proceed with the diagnostics from "Function Inspection Using M-MDS".

Details On DTCs

DETECTION CONDITION AND POSSIBLE CAUSE

DESCRIPTION	Thermostat stuck open
DETECTION CONDITION	Determination conditions	Actual engine coolant temperature does not exceed 71 °C {160 °F} even though the estimated engine coolant temperature after the engine is started exceeds 71 °C {160 °F}.
	Preconditions	Difference between ECT sensor No. 2 estimated temperature and value ^2 detected by ECT sensor No. 2 during malfunction determination is 13 °C {23 °F} or less Engine coolant temperature at engine start: 52 °C {126 °F} or less^1 IAT: -10-45 °C {14-113 °F}^1 Vehicle speed: 140 km/h {87 mph} or less^1 Engine speed: 5, 400 rpm or less^1 Idle ratio: 50 % or less The following DTCs are not detected: Fuel system malfunction: P0171:00, P0172:00, P2096:00, P2097:00 ECT sensor No. 1 malfunction: P0117:00, P0118:00 MAF sensor malfunction: P0102:00, P0103:00 ^1 : Value can be verified by displaying PIDs using M-MDS^*2 : Uses the ECT sensor No. 1 actual temperature or the estimated temperature, whichever one reaches 71 °C {160 °F} first, as the detection determination value.
	Drive cycle	2
	Self test type	CMDTC self test
	Sensor used	Desired engine coolant temperature: intake air temperature (IAT sensor), engine speed (CKP sensor), charging efficiency Actual engine coolant temperature: ECT sensor No. 1, ECT sensor No. 2
FAIL-SAFE FUNCTION	Not applicable
VEHICLE STATUS WHEN DTCs ARE OUTPUT	Illuminates check engine light. Heating is ineffective after engine is started
POSSIBLE CAUSE	ECT sensor No. 1 malfunction ECT sensor No. 2 malfunction Poor assembly of ECT sensor No. 1 Poor assembly of ECT sensor No. 2 Poor assembly of engine coolant hose (engine coolant passage malfunction) Poor engine coolant, leakage, or freezing Use of unspecified engine coolant Foreign matter caught in thermostat (foreign matter penetration in engine coolant) Thermostat malfunction PCM malfunction