Circuit Description

The ECT sensor is a thermistor that monitors coolant temperature. DTC P0116 is set when, after engine has been running for at least 20 minutes ECM detects a temperature of less than 19.4°F (-7°C) on THW circuit, and actual engine coolant temperature is 68°F (20°C) or less. DTC P0116 is also set when after engine has been running for at least 5 minutes ECM detects a temperature of 19.4°F (-7°C) or more, and less than 50°F (10°C) on THW, and actual engine coolant temperature is 68°F (20°C) or less. DTC P0116 is also set when after engine has been running for at least 2 minutes ECM detects a temperature of 50°F (10°C) or more on THW circuit, and actual engine coolant temperature is 68°F (20°C) or less. Possible causes are:

ECT sensor.
Engine cooling system.

NOTE: If DTCs P0115 and P0116 are output together, inspect ECT circuits for an open. Repair as necessary. See appropriate wiring diagram in SYSTEM WIRING DIAGRAMS article. Repair DTC P0115 first.