Re: what does the iat sensor do? (civic_type_r)
The IAT tells the ECU how hot the coolant is...duh.
C'mon now - IAT - intake air temperature - not that hard. Because Honda's use a Speed-Denisty type of fuel injection system, the volume of air entering the engine is not directly measured, as it is in a MAF based car. The temp of the air must be known to calculate this volume.
You can also use the ECT sensor as a reference value to compare to the IAT when the engine has been allowed to sit overnight. They share the same output characteristics.