the accuracy of the PID controllers isn't usually the problem; however, i found the auber RTD's to be of dubious quality, or i could just be really unlucky. i bought 2 last year. one was off by about 6 degrees, the other 15, from a 150 degree water bath. i recently bought 2 RTD's from omega.com, they were both spot on. the PID controllers were the same (2352's from auber).