2021 Mustang GT CHT error

[castek]

Hi all

I have a car that I am diagnosing a persistent overheat condition.

Car will randomly have the coolant temp gauge disappear (needle sitting at half like normal then it just disappears), says coolant overheating and go into limp mode, can barely drive the car like that.
Can literally clear the code as you are driving and its back to normal.

I have logged and thankfully, it did it on 3 of my logs, towards the end of all logs.

At the time of the overheat warning, it will throw P1299, Cylinder Head Overtemp.
When I look over the logs, eg Log 13overheat, the Coolant temp was at 192f and CHT was at 204f. I am led to believe these things shouldn't go into limp mode until CHT gets to 240f.
Voltage looks fine for the CHT, cannot log Coolant temp voltage.

I have done a lot of searching around, but can't find anything definitive. I thought faulty sensor, but surely I would see the voltage change as it trips the error.
Customer seems to think fuel supply issue, but from my logging (I will confess, I am predominantly a GM tuner), Fuel Pressure, AFR's etc are fine.

Car is a S550 platform mustang, Gen3 coyote. has the herrod s/c kit, which is the 3l whipple. car runs and drives great but customer doesn't enjoy the random tow truck calls or waiting for me to clear the code if he is local.

Any suggestions on what else i can look at? I really dont want to have to change the cht sensor, it looks like a nightmare, but if thats what it is, thats what it is.
cooling system is fine, i have bled it, no air etc. t/stat is working, pretty much checked all common things i could think of cooling related

thanks in advance

**just a quick edit to add, I did not tune this vehicle, that was done by the workshop that installed the blower. I will sort out fuel trims etc once we get this overheat issue

[veeefour]

Id replace the sensor and inspect the wiring.

Transfer function for CHT sensor is not something easily available and something anybody will ever change. ECT is inferred on those

[castek]

for those coming across this error, I have been able to, I think, sort it out. It seems with all the inferred info, being that it was originally tuned so lean, it seems the pcm was hitting overheat early to prevent the car actually overheating.
now i bang my head against the wall again as it is going super rich after wot, and it isn't the COT doing it as i have verified it as not being the fuel source