Diagnostic Aids

With the ignition ON, the engine OFF, if the engine is cold, a properly functioning IAT sensor 2 will gradually increase the scan tool IAT sensor 2 parameter. 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: 10Hz; -40°C (-40°F), and there are Humidity Sensor DTCs, check for a circuit problem.