Thermal dae miti off doesn't work

Hi there. I've got a problem with my lg optimus g. Since a few days my display throttles down although I activated Thermal dae miti off in the secret settings. I've tried all things. Restart after set this option on, take it off, wait one day and turn it on but nothing happend. 63% us to dark in the sun. I hope you can help me. Lg optimus g e975 4.4.2 v20a rooted, stock and locked bootloader.