DTC Detecting Condition and Trouble Area

DTC DETECTING CONDITION CHART

DTC detecting condition	Trouble area
DTC P0116: Engine Coolant Temperature Sensor 1 Circuit Range/Performance This DTC is detected if any one of the following conditions is met. Output voltage of ECT sensor signal circuit is unchanged for specified time (depending on ECT at engine starting) at cold start. Output voltage of ECT sensor signal circuit is unchanged even if variation of IAT is more than 2.5 °C (4.5 °F) and driving time is longer than 700 sec. after warm-up. (2 D/C detection logic)	ECT sensor and/or its circuit Thermostat ECM
DTC P0125: Insufficient Coolant Temperature for Closed-Loop Fuel Control ECT is lower than 10 °C (50 °F) for specified time even if elapsed time from engine stating is longer than specified time. (2 D/C detection logic)
DTC P0128: Coolant Thermostat Measured ECT is lower than 78 °C (172.4 °F) even if estimated ECT (depending on engine heat (calculated from MAF, fuel injection volume, etc.) reaches to about 89 °C (192.2 °F). (2 D/C detection logic)