Code 25: Mat Sensor Signal Volt High
Code 25 will set if the following conditions occur:
- Signal voltage indicates manifold air temperature is greater than 275°F (135°C).
- Vehicle speed is greater than 35 MPH.
- Both of the above requirements are met for at least 16 seconds.
Due to conditions necessary to set a Code 23, SERVICE ENGINE SOON light will stay on only while the fault is present.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- The "Scan" tester may NOT be used to diagnose this fault, due to the ECM transmitting default values. ECM and wiring are good if voltage is greater than 4 volts.
- If resistance is less than 185 ohms, replace sensor. See MAT SENSOR TEMPERATURE TO RESISTANCE VALUES table. INTERMITTENTS is located in H - TESTING W/O CODES article.