Code 25: Mat Sensor Temp. High (2.5L): Notes

1990 Chevrolet RV Cutaway 7.4 N, 475/M40SECTION Notes

The ECM applies and monitors a voltage signal (4-6 volts) to MAT sensor. When manifold air is cold, the sensor resistance is high and ECM sees a high signal voltage. As air warms, resistance decreases and voltage sensed by the ECM drops. Sensor resistance can be measured at sensor terminals with harness disconnected.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Test Number 1)  This checks if the code is a hard failure or an intermittent condition. Code 25 will set if a VSS signal is present and MAT sensor temperature is greater than 302°F (150°C) is sensed for more than 2 seconds.

RENDER: 1.0x

NO RELATED

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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