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 25 - Mat Sensor Temperature High: Notes
The ECM applies and monitors a voltage signal (4-6 volts) to circuit No. 472. When manifold air is cold, the sensor resistance is high and the ECM will see a high signal voltage. As air warms, resistance decreases and voltage sensed by the ECM drops. Sensor resistance can be measured at ECM terminals "B5" and "W14".
- Checks to determine if the code is a hard failure or an intermittent condition. Code 25 will set if a MAT temperature greater than 275°F (135°C) is sensed for more than 2 seconds.
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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.