Cylinder Head Temperature Sensor

So I have a check engine light that keeps showing P0125 as the code. I looked it up and it basically tells me that there is an issue in the temperature sensing of the engine coolant after 10-15 minutes of engine run time.

I live in Kansas and it gets cold sometimes, but I have had the car for more than a year and this is the first time I have seen this code. After doing some looking online I saw that there are several reasons for code to be thrown. I have not seen any issues with the car running rough or any major shift in fuel efficiency. I did have some issues with my temperature gauge not reading accurately, but in the quest to fix this problem, I have solved that issue.

So far I have replaced the two engine coolant temperature sensors (one for the computer one for the gauge) and the thermostat. I have been told that the code can sometimes be thrown due to CHT or air temperature sensor issues. Ialso have been told that the ZX2 often does not like non-motorcraft thermostats.

I have the air temperature sensor and the CHT and a motorcraft thermostat. Unfortunately, I cannot find any instruction online on how to replace the CHT. It would appear that the CHT is hidden very cleverly in the engine, I just can't see where to find it.

So my question is two fold:
1. Am I missing some part of the system that could be causing the code?

2. Where is the CHT located and how do I change it out?

I thought maybe the car doesn't have one, but the car part stores have them in stock, but it wouldn't be the first time the ZX2 and the ZX3 engines have been mistaken for each other in the autopart store computers, after all I have no air cabin filter on the ZX2 but there is one on the ZX3.

So, any help would be appreciated. Also, this problem came up after the first really cold morning. I get up, start the car, and drive 60 mph or more for the first 25 minutes of my drive. Oh, and I have already topped off the coolant multiple times, so low coolant levels are unlikely the cause.

Thanks!

Eric