2017 Silverado extended warranty work

[T-Man]

I just took my 2017 4x4 crew cab 5.3 into the dealership for extended warranty repairs. The front wheel bearing was noisy and loose, rear passenger door would not open from the inside, check engine light had popped on. When the extended waranty was sold at the purchase , I was told it was thru the Chevy company and just an extension of the factory bumper to bumper waranty. 93,000 miles with 100,000 mile waranty now. I get a call that the wheel bearing and door latch are covered . However the check engine light was diagnosed for my cost of 140 . The issue they say is loose spark plugs causing the misfire, so 498 to change plugs and diagnosis which isnt covered under the waranty since diagnosis uncovered a non waranty issue. I can`t believe it, if the manual said tighten plugs every x amount of miles then maintance issue , I would get that, but plugs loosening up , how can that be a maintanence issue if not stated in the manual to tighten in x amount of hours . Please respond with opinions , facts anything to help.         

[Gagliano7]

I doubt the spark plug loosened up unless some recently changed plugs and forgot to tighten one of them. I have never had to retighten a spark plug on anything i ever owned.

[jrabenaldt]

4 hours ago, Gagliano7 said:

I doubt the spark plug loosened up unless some recently changed plugs and forgot to tighten one of them. I have never had to retighten a spark plug on anything i ever owned.

Exactly!!!

[DeePa]

Fix the warranty stuff and tighten the plugs yourself