Thank you for choosing JustAnswer and allowing me to help you resolve your Toyota questions!
The last time I had this happen I had to replace the gage unit as an assembly to fix it. If you are certain the temp is not hot and the coolant level is full and circulating the issue will be related to the unit in the combination meter. If you can post a picture of the gages I can tell if it is the same style. The only other test you can do is the resistance test of the sending unit in the tank and the temp sensor in the engine. 14.2 volts is normal.
You can accept when you are satisfied that the help I have provided was useful. If you can get the Vehicle Identification Number I may be able to look up some other info. What country are you from? .
Rt hand drive? Auto Trans? EFI 2EE engine?
No rush it just kept popping up on my end saying you where requesting me.
That is a different combination meter then what is used here in the USA. If they both started acting up at the same time I would check the common earth points. then check the resistance of the sending units and make sure they are in line. My wiring info is limited on the world market Toyotas. If you would like I can transfer this to the UK category.
You are welcome. If you need anything or a second opinion let me know.
Nicely done, makes perfect sense, great pictures, good job.