The engine coolant temperature (ECT) sensor is a thermistor, or variable resistor, that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the ECT signal circuit through a pull-up resistor. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM detects an intermittently-low ECT signal voltage, a high temperature indication, this DTC will set.
| • | DTCs P0112, P0113, P1111, or P1112 are not set. | 
| • | The engine has been running for at least 10 seconds. | 
| • | The intake air temperature is less than 70°C (158°F). | 
The ECT sensor temperature is more than 149°C (300°C) for longer than 10 seconds.
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. | 
| • | The malfunction indicator lamp (MIL) will not illuminate. | 
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. | 
| • | The driver information center, if equipped, may display a message. | 
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. | 
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. | 
| • | Clear the DTC with a scan tool. | 
If the condition is intermittent, refer to Intermittent Conditions .
Step  | Action  | Yes  | No  | ||||
|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics  | |||||||
1  | Did you perform the Diagnostic System Check-Engine Controls?  | Go to Step 2  | |||||
2  | Are any other DTCs also set?  | Go to Step 3  | |||||
3  | 
 
 
 Did you find and correct the condition?  | Go to Step 4  | Go to Intermittent Conditions  | ||||
4  | 
 Does the DTC run and pass?  | Go to Step 5  | Go to Step 2  | ||||
5  | With a scan tool observe the Stored information, Capture info. Does the scan tool display any DTCs that you have not diagnosed?  | System OK  | |||||