weird voltage fluctuation...?

Volt gage shows like 10-11 volts at engine start (engine takes longer to start cause of low voltage) and a view seconds after start.....volts will go to normal......some times it takes a few minutes. Check engine light is on and codes 12,22,41 appear. this happened a few months ago and i cleaned everything up and it went away. it is now happening again but why???? I dont know what fixed it last time..... can anyone help? trying to fix asap going to pismo.

Check and clean the grounds

Concur. Check and clean the grounds, all the mains connections, and I'd also suspect the battery.

Since you're getting full voltage at RUN, the alternator is probably just fine - and the battery takes a "surface charge," but it loses it overnight. That's my thinking, and what I'd check first.

5-90