BUY WITH CARE

Collapsed Active Fuel Management (AFM) lifters are the defining engine defect of GM's 5.3L V8. Across the 2007-2019 Chevrolet Silverado 1500, Tahoe, Suburban and GMC Sierra 1500, Yukon, 959 of 30,462 complaint texts describe a failed valve lifter -- the deactivating AFM/DFM lifters seize or collapse, most often on a cylinder that shuts off under light load. It shows up as a ticking or tapping noise, a cylinder misfire (typically a P030x code) and a check-engine light, and in the worst cases the engine drops into limp mode or loses power at speed: 230 of those texts describe limp mode, lost power, a stall, or a shutdown. A collapsed lifter can also wipe the camshaft lobe, turning a lifter job into a top-end rebuild. Median reported mileage is ~96k, and the failure spikes on the 2019 refresh (314 lifter texts that year alone, when DFM arrived).

Check — Listen for a lifter tick at idle and under light throttle, and scan for cylinder-misfire codes (P0300-P0308) and camshaft-correlation history. Ask whether any lifter, camshaft, or top-end work has been done -- a well-documented AFM/DFM-delete or lifter replacement is a plus, not a red flag.