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Home >> Chevrolet >> 1990 >> APV >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - TBI >> Diagnostic Tests >> Code 25: Mat Sensor Temp. High (2.5L) >> Diagnostic Aids
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Diagnostic Aids

If the engine is allowed to cool overnight, the coolant temperature sensor and MAT sensor should read close to each other, when measured with a "Scan" tester. A Code 25 will also result if sensor signal circuit is shorted to ground.

Fig 1: Code 25: MAT Sensor Temp High (2.5L)
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