SHDN OVRD button?

Please I have a problem with my 05 freighlinner columbia, the check engine and engine protect lights come on at 1500rpm and cuts power and lights goes off and comes back on as soon as it gets to 1500rpm again. Anybody have an idea

 

Just don't push the EJCT button!

 

I have 07 century with D60 I just hit that button and see a red check egine light come on lol, and hit it back again and it changed to yellow the reason i did that was my check engine light was on due to temp gauge was acting funny going up and down and not working and the fan stays on thinking that the truck is over heated while i have enough coolent, i changed the coolent sensor and nothing has changed , then i replaced a temp sensor which is in the back side of the engine and it is very hard to get in and very hot coolent will come on if the truck was ruuning, now the temp gauge is working fine but i have the check engine light is on ..... looking for another solusion and will be updated