Coolant temp probe breaker wiring?

What do you consider high oil and CHT's?

CHT was about 270+ 

Oil temp was pretty close to this too.

Temps were high for about 20-30 min.

270+ is pretty high. Verifying if that’s a reliable reading seems a good idea.

However, the typical VDO sensor delivers a resistance (dropping with increasing temp). A breaker or fuse or anything like this is not needed.

There are in fact different versions available (check C-rating: 120C or 150C). Their resistance curves differ. If your gauge expects a particular sensor but another one is installed you will get continuously false readings.

I don't think it's the sensors because it's two different sensors in two different spots showing a similar reading. You don't need a separate water sensor. You just need to find the source of the problem. Your temps are high and adding another water temp probe will only tell you the same thing, but won't be a solution to the problem. 

There are several things that can cause a high temp. What aircraft is this and is it tightly cowled? Did this just all of a sudden start the high temp issue? At what rpms does this occur i.e. on the ground idling or in flight? Have you had any recent work done? What coolant are you using? Is everything else normal, but the two temps? 

Hi, I just had a brief look at the two restistance curves of the 120C and the 150C VDO temp sensor versions that are commonly used withn Rotax 912 engines.
To get propper readings your gauge expects either or - they do not deliver the same restinace valus at a given temperature!
According to their specs the 120C type will give 22,4 ohms at 120 degree celsius - the 150C type wil provide 36,5 ohms for the same temp.
If the 150C type is expected by your gauge but the 120C type is installed (they look pretty much the same) the readings will be too hot. The gauge is supposed to show 120 degree Celsius on the basis of 36,5 ohms. But what it gets from a 120C type is 22,4 ohms (which stands for aprox. 140 degee Celsium from the 150C type).
You can easily check which type you have installed - normally the temp is shown on the hex-collar of the sensor.
Good luck!