Circuit Description

The ECT sensor is a thermistor that monitors coolant temperature. DTC P0116 is set when after engine has been running for 20 minutes ECM detects a temperature of less than 20.5°F (-6.4°C) on THW or THA 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 5 minutes ECM detects a temperature of 20.5°F (-6.4°C) or more, and less than 50°F (10°C) on THW or THA, and actual engine coolant temperature is 68°F (20°C) or less. DTC P0116 is also set when after engine has been running for 2 minutes ECM detects a temperature of 50°F (10°C) or more on THW or THA 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.