6.2L V8 connecting-rod / crankshaft failure — recall 25V274
CoveredThe defining 2021 issue if the truck has the 6.2L. GM recalled about 597,571 vehicles (2021–2024 Silverado, Sierra, Tahoe, Yukon, Escalade) for connecting-rod and crankshaft manufacturing defects that put debris in the oil and can cause sudden engine failure — 'no warning, just died' in the file — with NHTSA expanding its probe twice. GM estimates roughly a 3% defect rate; the remedy inspects and repairs or replaces the engine free, and moves these to 0W-40 oil. A used 6.2L that's been through the recall (check for the 0W-40 spec and Carfax record) is a known quantity; one that hasn't is an open question. Confirm completion by VIN.
Sources: NHTSA complaint database, 2021 Silverado 1500 · NHTSA recall database and manufacturer communications (recall 25V274; transmission-valve coverage; eBoost CSP)
5.3L Dynamic Fuel Management (DFM) lifter failure
$3,000–$10,000If it's the 5.3L, the lifter issue rides on. DFM can deactivate any of all eight cylinders, and mechanics say its lifters fail more often and earlier than the older AFM — a tick, misfire, power loss, and a $3,000–$10,000 repair with no recall, only a class action and reactive warranty repairs. A DFM disabler (~$150) is cheap prevention and a cold-start tick is the walk-away sign. Between the two engines, the 6.2L's risk is largely covered by the recall while the 5.3L's lifter risk is not — factor that into which one you buy.
Sources: NHTSA complaint database, 2021 Silverado 1500 · Independent mechanic channel transcripts (T1XX Silverado; AFM/DFM lifter deep-dives)
8-speed transmission — costliest failure is covered
CoveredThe 8-speed can still shudder and shift harshly, but the expensive control-valve failure is covered on this year by GM's 15-year/150,000-mile Special Coverage (from the in-service date, regardless of ownership) — a new valve body free, with reimbursement for prior repairs. The 10-speed on other trims is the stronger unit. Test-drive for shudder and hard shifts, and confirm the truck is inside the coverage window.
Sources: NHTSA recall database and manufacturer communications (recall 25V274; transmission-valve coverage; eBoost CSP) · Independent mechanic channel transcripts (T1XX Silverado; AFM/DFM lifter deep-dives)