2010 M8 high temp reading

[knee deep in it]

I was at Castle last weekend and the temp kept rising. The rear cooler was not hot and coolant level was normal. The engine definately was not overheating yet the reading kept climbing all day. ( 212F on the way back to the trailer)

Turning the sled off for 10 minutes did not change anything. It was 205F when I turned it off and, 10 minutes later, it was 205 when I started it. I am 99% certain it is the sensor.

Before I change it, can anyone confirm my diagnosis?

 

[Rjjtcross8]

You may have done this during your diagnosis, but have you ruled out an airlock?

 

[knee deep in it]

an airlock would have caused a genuine raise in temperature. the temp was normal despite the high readout on the dash.

 

[oilrecycler]

probably too many miles on it

 

[Modman]

I was at Castle last weekend and the temp kept rising. The rear cooler was not hot and coolant level was normal. The engine definately was not overheating yet the reading kept climbing all day. ( 212F on the way back to the trailer)

Turning the sled off for 10 minutes did not change anything. It was 205F when I turned it off and, 10 minutes later, it was 205 when I started it. I am 99% certain it is the sensor.

Before I change it, can anyone confirm my diagnosis?

Haven't heard that before, only real way to verify without replacing would be to take a thermometer and check the coolant temp as it was circulating or put an additional gauge on it. The sensors usually aren't the issue, usually its the t-stat. Not sure 100% I would have to go back to the manual but I think they start to retard ignition timing and/or won't even run above a certain temp (want to say its around 170-180 but don't quote me.....) and I don't think its anywhere near 200.