2025 GMC Sierra 1500 Service and Repair Manual

GMC's half-ton pickup spans eight trims for 2025, from the fleet-minded Pro through SLE, Elevation, SLT, the off-road AT4 and AT4X, and the Denali and Denali Ultimate. The diesel is the headline: the 3.0L Duramax inline-six moves to the LZ0 version with more power and torque, alongside the turbocharged 2.7L four and the 5.3L and 6.2L V8s. Trim decides which engines are available, so year-exact data matters when ordering parts or looking up a torque value. This factory service and repair manual is arranged by system and engine, with procedures, specifications, wiring diagrams, diagnostics and maintenance schedules.

Engines covered

• 2.7L inline-four — DOHC, turbocharged, gasoline
• 3.0L inline-six — DOHC, turbocharged, diesel
• 5.3L V8 — OHV, naturally aspirated, gasoline
• 5.3L V8 — OHV, naturally aspirated, flex-fuel
• 6.2L V8 — OHV, naturally aspirated, gasoline

Body styles covered

• 4-door crew cab pickup
• 4-door extended cab pickup
• 2-door standard cab pickup

Trims covered

• AT4
• AT4X
• Denali
• Denali Ultimate
• Elevation
• Pro
• SLE
• SLT

Known issues on the 2025 Sierra 1500. One recall is on federal record, and it concerns aftermarket equipment rather than the truck itself: Rollx QRT-Deluxe and QRT-Max wheelchair restraints installed in mobility conversions may not hold a wheelchair securely. Owners have lodged 116 complaints, led by the engine, the power train and the electrical system. Engine mechanical, driveline and electrical diagnostics are all detailed in this manual with torque values and wiring diagrams.