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, ECT Circuit High/Low Temperature Indicated: Notes
Engine Coolant Temperature (ECT) sensor uses a thermistor to control signal voltage to ECM. ECM applies voltage on Gray/Black wire to sensor. When engine is cold, sensor (thermistor) resistance is high. ECM will then sense high signal voltage.
As engine warms, sensor (thermistor) resistance decreases and ECM senses low signal voltage. When engine reaches normal operating temperature, signal voltage will be approximately 1.5-2.0 volts at ECM terminal C10. Engine coolant temperature is one of the inputs used by ECM to control fuel delivery, Ignition Control (IC) and Idle Air Control (IAC).
- Checks if code is due to a hard failure or intermittent condition. Code 14 will set if signal voltage indicates engine coolant temperature greater than 412°F (213°C) for 3 seconds. Code 14 will also set if engine has been running for at least 2 minutes and engine coolant temperature is less than -35°F (-37°C).
- Simulates conditions for Code 14 (low temperature indicated). If ECM senses open circuit (high voltage) and displays low coolant temperature, ECM and wiring are okay.
- Determines if ECM and/or wiring is faulty.
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.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.