I'm bleeding my coolany system and when I close the bleed screw on the thermostat, my check engine light is coming on (solid). When I open the bleed screw, it goes off.

My temperature needle is closer to the cold blue than the middle which is also kind of weird since about 10 minutes before that, it was 3/4 of the way to Red.

Curious about the check engine light and is my thermostat going?