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, Manifold Air Temperature (Mat) Sensor (Temperature Too High): Notes
The MAT sensor uses a thermistor type resistor to control signal voltage to the ECM. A 4-6 volt reference signal is supplied to the sensor on circuit on circuit No. 472. When manifold air temperature is cold, sensor resistance is high and the ECM will see a high signal voltage. As the manifold air temperature rises, sensor resistance becomes less and voltage drops.
Test Number 1) This step checks if Code 25 is a result of a hard failure or an intermittent condition.
A Code 25 will set if:
- Signal voltage indicates a MAT temperature greater than 275°F (135°C) has been detected for longer 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.