2020 GMC Sierra 2500 HD

The 2020 GMC Sierra 2500 HD is a heavy-duty pickup truck known for its towing and hauling capabilities. Available engine options include a 6.6L gasoline V8 producing 401 horsepower and 464 lb-ft of torque and a 6.6L Duramax turbodiesel V8 producing 445 horsepower and 910 lb-ft of torque. The gasoline engine is paired with a 6-speed automatic transmission, while the diesel engine is paired with a 10-speed Allison automatic transmission. Owners generally appreciate the truck’s robust capabilities, comfortable interior (especially in higher trims), and updated technology. Some common dislikes include the relatively stiff ride (typical for heavy-duty trucks) and the high price point.

Engine

6.6L Gasoline V8

• Active Fuel Management (AFM) / Dynamic Fuel Management (DFM) Lifter Failure
  • Description/Symptoms: Engine misfires, rough running, check engine light illuminated. Often diagnosed with a failed lifter, which can damage the camshaft. This failure is often caused by oil starvation or a faulty lifter design.
  • Solution: Replacement of the affected lifters and camshaft. In some cases, full engine replacement may be necessary if the damage is severe. Some owners choose to delete the AFM/DFM system during the repair to prevent future issues.
  • Estimated Cost to Fix: $3,000 - $6,000+
  • Recalls: None Found

6.6L Duramax Diesel V8

• CP4 Fuel Pump Failure
  • Description/Symptoms: Engine stalling, difficulty starting, check engine light illuminated. The CP4 high-pressure fuel pump is known to self-destruct, sending metal shavings throughout the fuel system. This contaminates the injectors, fuel rails, and fuel lines.
  • Solution: Replacement of the CP4 fuel pump and thorough cleaning or replacement of the entire fuel system, including injectors, fuel rails, and fuel lines. Some owners proactively replace the CP4 pump with a more robust CP3 pump as a preventative measure.
  • Estimated Cost to Fix: $8,000 - $12,000+
  • Recalls: None Found
• EGR Cooler Failure
  • Description/Symptoms: Loss of coolant, white smoke from the exhaust, engine overheating. EGR cooler cracks can allow coolant to enter the exhaust system.
  • Solution: Replacement of the EGR cooler.
  • Estimated Cost to Fix: $1,500 - $3,000
  • Recalls: None Found

Transmission

6-Speed Automatic (Paired with 6.6L Gas V8)

• Torque Converter Shudder
  • Description/Symptoms: Vibration or shudder during light acceleration, especially at lower speeds.
  • Solution: Transmission fluid flush with updated fluid, torque converter replacement.
  • Estimated Cost to Fix: $500 - $2,500+
  • Recalls: None Found

10-Speed Allison Automatic (Paired with 6.6L Duramax Diesel V8)

• Harsh or Delayed Shifts
  • Description/Symptoms: Rough shifting between gears, delays in shifting, especially when cold.
  • Solution: Software re-flash of the transmission control module (TCM). In some cases, valve body replacement may be necessary.
  • Estimated Cost to Fix: $100 - $3,000+
  • Recalls: None Found

Suspension

• “Death Wobble”
  • Description/Symptoms: Violent shaking or oscillation of the front end, especially at higher speeds after hitting a bump or imperfection in the road.
  • Solution: Often requires replacing multiple front-end components, including the steering stabilizer, ball joints, tie rod ends, and potentially the steering gear box.
  • Estimated Cost to Fix: $500 - $2,000+
  • Recalls: None Found

Electrical

• Infotainment System Issues
  • Description/Symptoms: Freezing, rebooting, black screen, connectivity problems with Apple CarPlay or Android Auto.
  • Solution: Software updates, replacement of the infotainment screen.
  • Estimated Cost to Fix: $0 (software update) - $1,500+ (screen replacement)
  • Recalls: None Found
• Battery Drain
  • Description/Symptoms: Battery draining overnight or after a short period of inactivity.
  • Solution: Diagnosis to identify parasitic draw. Common causes include faulty modules (e.g., radio, OnStar), aftermarket accessories, or a failing battery.
  • Estimated Cost to Fix: $100 - $500+
  • Recalls: None Found

Exterior

• Bed Bounce/Vibration
  • Description/Symptoms: Excessive bed bounce or vibration, particularly noticeable when driving on uneven surfaces or at highway speeds.
  • Solution: Some owners have had success with aftermarket solutions such as installing shims or modifying the bed mounts. No consistent fix from the manufacturer.
  • Estimated Cost to Fix: $50 - $500+ (aftermarket solutions)
  • Recalls: None Found
• Rear Tailgate Issues
  • Description/Symptoms: Tailgate not opening/closing properly, tailgate power functions failing, damaged/loose tailgate trim.
  • Solution: Repair or replacement of the tailgate latching mechanism, wiring, or tailgate itself.
  • Estimated Cost to Fix: $100 - $1,000+
  • Recalls: None Found

Interior

• Heated Seat Malfunction
  • Description/Symptoms: Heated seats not working, overheating, or only partially heating.
  • Solution: Replacement of the heating element or control module.
  • Estimated Cost to Fix: $200 - $800+
  • Recalls: None Found
• Cracked Dashboard
  • Description/Symptoms: Cracking of the dashboard material, especially in areas exposed to sunlight.
  • Solution: Dashboard replacement.
  • Estimated Cost to Fix: $800 - $2,000+
  • Recalls: None Found

Summary

The 2020 GMC Sierra 2500 HD, while a capable truck, can suffer from some significant issues. The CP4 fuel pump failure on the diesel engine and lifter failures on the gasoline engine are particularly concerning due to their high repair costs. Electrical gremlins, bed bounce and tailgate issues are also prevalent. Severity of issues range from minor infotainment problems to catastrophic engine or transmission failures. Depending on the issue, the costs can range from a few hundred dollars for software updates to upwards of $10,000 for major engine or fuel system repairs. Potential buyers should be aware of these common issues and have the vehicle thoroughly inspected before purchase.