I mostly just drive it to work and back about 25-30 minutes each way, and every day when I got home from work and turned off the engine it would come on a do a regen cycle, for varying amounts of time(usually 3-5 minutes). But lately when I get home the fan acts like it wants to turn on but can't do it. It makes noise like the fan starts to spin and then shuts off, and most of the time it will do this multiple times, but I've only had the full cycle happen 1 time that I remember in maybe the last 2 weeks or so. I can even sometimes hear it doing the same thing while the car is on. Not sure if it's an issue with the fan itself or maybe a sensor or something. Any thoughts or ideas would be appreciated.