2007 Lexus IS iat sensor

The IAT sensor is in air filter box.

I have to tell you that these types of fuel economy devices can sometimes cause more problems than they are worth.

The IAT (incoming air temp) sensor measure incoming air temp to engine to set air/fuel ratio (among other sensors).

These devices "trick" the PCM telling the PCM that the air temp is hot, the PCM then sets fuel to a lean setting, saving fuel but causing engine to run lean.

This can cause high combustion temps, and possible damage to convertor over time.

If it were to cause damage to convertor, Lexus would not warranty repair as it considers these devices as "unapproved".