Hey Guys...just a general question, over the last two years I have had to replace three engine coils which the dealership charges between 250-450 to replace. What is causing the failure and is the occurence out of the norm?
Have just over 70k on the truck but have had one fail about every 8-9 months like clockwork

 

What codes did you get prior to the failure ? Some of the problems are not the coil,but the boot(grounding problems). A liberal application of dielectric grease in the boots will solve many a problem.

 

If one goes bad, it's very likely others will follow, which is what's happening with you. Each of the 8 coils is crapping out due to a variety of causes, think a poor ground is the most likely cause.

Next time you bring it in (or DIY to save some $$$) request that all 8 be changed. You won't and unlikely the dealer will know which have been swapped already and which haven't, so just end the headache once and for all and replace them all.