JHall- va

09/23/2019: Similar issue here, recently...P0307 Code/ Engine Light... Was told by my local GM Dealer - that they would NOT rebuild the engine, and that they would only "replace" the engine with this issue...well over $7,000 to do this! My #7 plug is "Fouled"...causing the mis-fire and is in fact leaking oil. Unfortunately, my truck (2014 Suburban) has 86,000 miles on it - and NOT under Powertrain Warranty! Any advice?? thanks - John