Weird coolant temperature incident.

[Rafichicago]

So this morning I went to fire car up. It’s 06 3.0 SI with N52. It’s cold here so I like it to sit and idle before the drive. Since it’s my wife’s current daily she worked out and immediately called me to come down. The car idled with fan at full speed. It was maybe 5 mins later at most. I walked down and checked gauges. Immediately noticed the coolant temp all the way at red. I shut the car down than I started thinking. Something was weird. I popped the hood and I was like… it’s not hot here. Checked for leaks and none were present. Opened the coolant expansion tank carefully and I added maybe a 100ml. And it wasn’t hot at all. I have restarted the car and this time coolant temperature was hardly raised. Weird I thought. Drove the car. It would drive fine and held temperature since. I was dropping off for oil pan gasket anyway so it was checked for any stored codes and there was none. I suspect it’s one of coolant temp sensors. Which one is responsible for what’s gauge is showing ? Is it the one on one of the radiator hoses or the one in front of the engine ? Let me guys know what you think.

[Efthreeoh]

Do you know what scan tool was used to scan the car? An OBD2 scan tool will not find waterpump codes. It sounds like the waterpump did not start when you had the car idling. Upon restart, the pump worked.

[Rafichicago]

Car is at the dealer so whatever they’re using. If that would be the pump the car would actually overheat which it didn’t, since I’ve opened the coolant reservoir and it wasn’t hot. It was nowhere near the temperature that the gauge would be showing. I’d think that occurrence would leave the trace but apparently it didn’t. Oh well…