Diagnose - that doesn't mean blindly believe the red light.
Options - what are the variables? If I'm in the granite infested cloud I'm less inclined to shut down an engine that is providing power without smoke.
Decide - choose one of your options.
Act - get on with your chosen option.
REVIEW - is it going to plan? Probably the most important bit of the whole process.
PS. I've lost count of the number of binned/abridged sorties I've had due to sensor error. I've yet to have an engine fire.