I had to calibrate my TPMS a few times over the past two weeks, after receiving warning for low pressure (finally it was a nail). Each time I run the calibration as described in the manual, but never got the dots turn green even after driving for more than half an hour during the same engine run cycle, as described in the manual. At restart the dots turn green, but the manual says they will, even if calibration is not complete..So my question is, to anyone who has done the calibration before, how long does it take to complete the calibration? Have you seen the dots turn green before switching off the engine?