[Spectre]

Okay, I seem to have a problem. I've searched around and figured out the Cooper S has a power steering fan and a two speed radiator auxiliary fan. Yesterday I parked my car in a driveway and left it running while I walked around a house to take a look inside. When I returned, the temperature gauge was red lined. I pulled out of the driveway and rolled away and the gauge immediately went back to half way. It happened again tonight while stuck in some traffic. It did it twice. Both times, it seemed to come right back down as soon as I was able to get rolling again. No water overflowed nor did I smell any signs of overheating. I didn't hear the "loud" fan that usually kicks on when I'm sitting at a drive thru or after driving the car hard and then idling.

When I got home tonight I left the car running to see if the fan kicked on. A fan did kick on but it was very quiet, not the usual vacuum cleaner sound. After reading some similar posts, I believe this was the power steering fan. I've also deduced the power steering fan only comes on when the auxiliary fan runs. The gauge did not red line while it sat in my driveway. I’ve checked the fuses and they seem to all be fine. My question is how do I check the relay? Is this a possible sensor problem?