Code 25, Intake Air Temp Sensor CKT, High Temp Indicated: Notes

IAT sensor uses a thermistor to control signal voltage to ECM. ECM applies 5 volts on Gray wire to sensor. When manifold air is cold, sensor resistance is high. ECM will sense high signal voltage. As air temperature warms, sensor resistance will reduce and voltage will drop.

Code 25 will set if voltage input at ECM indicates an air temperature of greater than 277°F (136°C) for at least 3 seconds.

1. This test simulates Code 23. If ECM stores Code 23, ECM and its wiring are okay and IAT sensor is faulty. If Code 25 resets, IAT sensor is okay and wiring to ECM or ECM is faulty.