Diagnostic Aids

With the ignition ON, when the engine is cold and not running, properly functioning IAT sensor 2 will gradually increase the scan tool IAT Sensor 2 parameters. This is due to the heat that is generated by the multifunction intake air sensor heating elements.
The humidity sensor and the IAT sensor 2 signals are sent to the ECM on the same circuit. If the IAT Sensor 2 parameter displays the values: 10 Hz; -40°C (-40°F) and there are also Humidity Sensor DTCs, check for a circuit problem.