What is the correct Mazda plug for the 2014-2015 Mazda 6 2.5L? Mazda Dealer took out PE5R-18110 and put in the P51R-18110 per the paperwork. They did both my 2014 and 2015. I'm quetioning the service because on the 2015 I noticed they didn't tighten the coil pack screws. All were very loose and one had 10+ threads showing. Also they neglected to blow debris off the engine top surrounding the plugs. The 2014 was fine, btw.

 

While I can't absolutely confirm but I think someone transposed the numbers on the service order. I really didn't look too far only for a champion ,autolite or NGK cross reference to both those numbers? MAZDA does not have a spark plug engineering specification guide, so it makes it challenging at times when you want to know what was on the minds of the powertrain development departs at various auto manufactures choosing which heat range and type of spark plug design to choose. And contrary to a widely though belief it is not always "ENGINEERS! lol
As for the coil pack not being secure this really show poor service work. But to tell you the truth it would not have been likely that the coil pack would have lifted completely off if any at all so yu were not really in trouble had you not caught the unsecured coil packs.

I would recommend not to use the service establishment again !!!