I located mine on the engine cooling baffle near the cooling inlet opening. It's accurate with the engine operating and is pretty close with the aircraft idle in the sun after an overnight cool. The sun will have some effect regardless of where you put it. Obviously it reads hotter after engine shut down but I have not found that to be a problem. On the fast aircraft, impact heating of the airstream raises the reading if the probe is in the clean airstream. Impact heating is negligible in the suggested location since the cooling airflow over the engine is at a much reduced speed. During taxi mine agrees with the automated weather at the airports. This location avoids most of the drag of the probe for the purists plus places it out of harms way for ramp/cleaning damage.