Mike, I've never heard of any pre maintance on the otterstat and I have taken some out that were original and still working. I would carry a spare for safety. John Hervey www.special T Auto.com << Just curious, how often should the otterstadt switch be replaced. Can the sensor become coated with crude after a few years. I replaced mine about three or four years ago and was wondering what the replacement time should be. They're not that expensive and pretty easy to change so thought it might be worth changing again. I don't drive that much so maybe that figures into it as well. >>