Circuit Description

The ECT sensor is a thermistor that monitors coolant temperature. If DTC P0116 is set, ECM will operate in a fail-safe mode, in which engine coolant is assumed to be 176°F (80°C). DTC P0116 is set when after engine has been running for 20 minutes ECM detects a temperature of less than 19.4°F (-7°C) on THW circuit, and actual engine coolant temperature is 95°F (35°C). DTC P0116 is also set when after engine has been running for 5 minutes ECM detects a temperature of less than 50°F (10°C), or detects a temperature equal to or grater than 19.4°F (-7°C) on THW circuit, and actual engine coolant temperature is 95°F (35°C). DTC P0116 is set when after engine has been running for 2 minutes ECM detects a temperature of more than or equal to 50°F (10°C) on THW circuit, and actual engine coolant temperature is 95°F (35°C). Possible causes are:

ECT Sensor
Faulty Cooling System

NOTE: If DTCs P0115 and P0116 are output together, diagnose DTC P0115 first. Inspect engine coolant temperature circuit for an open. Repair as necessary. See appropriate wiring diagram in SYSTEM WIRING DIAGRAMS article.