Code 25, Intake Air Temperature High: Notes

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

1. This checks if code is a hard failure or an intermittent condition.
2. This simulates conditions for a Code 23. If scan tester displays a low temperature, control module and wiring are not at fault.