I wondered how accurate built in pressure readings are. I was having trouble getting pressure settled at recommended so bought a cheap gauge. Ignore gauge and go with displayed pressure(2014)? Hand held gauge reading 3 psi less all around. This whole process started because dealer suggested 38/42 instead of 33/38. VW says no way. I have gone so far as to buy a highly rated gauge to see if any difference. Does built in gauge ever need re-calibrating?