Just had my 6.6 duramax diesel worked on . Got a diagnostic done becauce of truck blowing white smoke . codes came back , bad air flow sensor, bad egr valve selinoid, air filter, and egr valve system needs to be cleaned out all of this was done , truck still blowing white smoke . Also has a bad glow plug that wasnt fixed . .Chweck engine light came back on as i was driving home. The mechanic said i need to let it blow out itself which takes a week or two. And stated the white smoke is also due to the bad glow plug, Is this correct,,Please advise..

Glow plug shouldn't affect the truck when driving as they are primarily used to start the engine. I could be wrong.....

I had white smoke from my truck when the PCV bypass tube I installed got clogged. Never threw a CEL though. I cleared the tube and the smoke went away after about 5 minutes.

I'd get a second opinion.