Trouble CodesGM OBD Trouble CodesGM Code 14

CODE 14 - Coolant Temp Sensor Circuit

Trouble Code 14 indicates that the Coolant Temperature Sensor (CTS) is reporting abnormally high readings. CTS is used to control fuel mixture, timing, idle speed, TCC and EGR operations among others. The thermistor used has a low resistance when hot, rising as the coolant cools. This error then, indicates a very low resistance in the CTS circuit.

The conditions for setting this code are:

  • the coolant temperature reported is > 284 deg F (140 deg C), and
  • the above condition is present for more than 20 seconds

NOTE: A default temperature of 111 deg F is used while the error is present.

Typical thermistor resistance values are:

CTS Resistance Chart

Typical causes for this code include:

1) Severe engine overheating
2) Defective Coolant Temperature Sensor (resistance too low)
3) Short circuit in CTS-ECM harness
4) Defective ECM

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