Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code 14, Coolant Temperature Sensor (Cts) Circuit High Temperature Indicated: Notes
The coolant temperature sensor uses a thermistor to control signal voltage to the ECM. The ECM applies voltage on the Gray/White wire to the sensor. When engine is cold, thermistor resistance is high. This means the ECM will see high signal voltage.
As engine warms, thermistor resistance is less. This means the ECM will see low signal voltage. When engine reaches normal operating temperature of approximately 176-203°F (80-95°C), signal voltage will be approximately 1.5-2.0 volts at the ECM.
- Code 14 will be set if signal voltage indicates coolant temperature is less than -54°F (-48°C) for 3 seconds.
- This simulates a Code 15. If ECM sees the low signal voltage and sets a Code 15, the ECM and wiring are okay. If Code 14 sets again, problem is an open Gray/White wire or Light Green/Black wire, poor connection at ECM or faulty ECM.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.