EGT keeps at max 600F

Hi folks

I'm experiencing an issue with EGT in my CTLS.

When I started the engine both EGT start increasing but it stops exactly at 600°F, some times 599F, but it never exceed 600F (see the picture attached). But CHT indication is working normal.

I tried replacing both thermo couple but keeps at max 600F. I tried heating one of the thermo couple with a lighter and it inmediatly increase above the 600F, so I guess it's not a thermo couple issue.

Do you guys have any idea or recommendation?