P0307

P0307 means cylinder 7 is misfiring, which restricts you to V8s, V10s, V12s, and inline-8 engines — in modern shop work, that's almost always a V8. Standard diagnostic flow applies: read the plug, swap the coil with an adjacent cylinder on the same bank, swap the plug, compression test, injector balance test. Cylinder 7 location varies sharply by manufacturer: on a Ford 4.6L/5.4L modular V8, cylinder 7 is on the left (driver's) bank, third from the front. On a GM LS-series V8, cylinder 7 is on the left (driver's) bank, third from the front (similar to Ford but the bank assignments differ on transverse applications). On a Chrysler 5.7L/6.4L Hemi, cylinder 7 is on the left bank, third from the front. On a BMW N63/S63 twin-turbo V8, cylinder 7 is on the right bank rear and notorious for heat-related coil failure. Pull the FSM diagram before touching anything.

Vehicle-specific patterns: 2004-2010 Ford F-150/Expedition with the 5.4L 3V is the most common P0307 ticket in North American shops — stuck plugs, cam phasers, and coil-boot carbon tracking on the left bank. 2007-2014 GM 5.3L (LMG, LC9) trucks/SUVs with Active Fuel Management frequently throw P0307 from the AFM lifter collapse — cylinder 7 is one of the deactivated cylinders and the lifter fails to reactivate, causing a hard misfire; the fix is a full AFM-delete kit or lifter replacement. 2008-2014 BMW N63 (550i, 750i, X5/X6 5.0i) throws P0307 from the well-documented coil-pack and injector failures that BMW addressed via a Customer Care Package extending warranty coverage. Estimated repair: $40 (single coil) to $4,000+ (AFM lifter job on the 5.3L).