The engine coolant temperature (ECT) sensor is a thermistor, or variable resistor, that measures the temperature of the engine coolant. The PCM supplies 5 volts to the ECT signal circuit through a pull-up resistor. When the engine coolant temperature is cold, the sensor resistance is high. When the engine coolant temperature 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 diagnostic trouble code (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 (IAT) is less than 70°C (158°F). |
• | The ECT sensor temperature is more than 149°C (300°F) for longer than 10 seconds. |
• | The condition exists for at least 1 second. |
• | 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 |