2021 GMC Sierra 2500 HD
Alright, here’s a breakdown of common issues and complaints for the 2021 GMC Sierra 2500 HD, formatted as requested.
The 2021 GMC Sierra 2500 HD is a heavy-duty pickup truck known for its towing and hauling capabilities. Engine options include the 6.6L L8T gasoline V8 engine producing 401 horsepower and 464 lb-ft of torque and the 6.6L L5P Duramax turbodiesel V8, delivering 445 horsepower and 910 lb-ft of torque. The gasoline engine is paired with a 6-speed automatic transmission, while the diesel utilizes a 10-speed Allison automatic. People often praise the Sierra HD for its comfortable ride (especially with the independent front suspension), strong towing capacity, and available technology. Common complaints include the truck’s large size making it difficult to maneuver in tight spaces, the high price tag, and some interior materials feeling less premium than expected for the cost.
Engine
6.6L L8T Gasoline V8
- Valve Lifter Failure
- Description/Symptoms: Ticking or knocking noise coming from the engine, especially at idle. Can lead to misfires and reduced engine performance. This issue seems to be more prevalent in the earlier production runs of the L8T.
- Solution: Replacement of the failed valve lifters and potentially camshaft if damaged.
- Estimated Cost to Fix: $2,000 - $4,000+
- Recalls: None Found
- Catalytic Converter Failure
- Description/Symptoms: Check engine light, reduced engine performance, rattling noise from exhaust. Can be caused by excessive oil consumption or other engine issues.
- Solution: Replacement of the failed catalytic converter.
- Estimated Cost to Fix: $1,000 - $3,000+
- Recalls: None Found
6.6L L5P Duramax Turbodiesel V8
- CP4 High-Pressure Fuel Pump Failure
- Description/Symptoms: Engine stalling, difficulty starting, check engine light. The CP4 pump is known to be less tolerant of contaminated fuel than previous designs.
- Solution: Replacement of the CP4 pump and potentially the entire fuel system depending on the extent of the damage from metal debris.
- Estimated Cost to Fix: $9,000 - $12,000+
- Recalls: None Found
- Diesel Exhaust Fluid (DEF) System Issues
- Description/Symptoms: Check engine light, reduced engine performance, messages related to DEF quality or level. Problems can arise with the DEF injector, DEF tank heater, or sensors.
- Solution: Diagnosis and replacement of the faulty component (injector, heater, sensor, etc.).
- Estimated Cost to Fix: $200 - $2,000+ depending on the component.
- Recalls: None Found
- Turbocharger Failure
- Description/Symptoms: Whining or screeching noises from the turbo, loss of power, excessive black smoke from the exhaust.
- Solution: Replacement of the turbocharger.
- Estimated Cost to Fix: $2,500 - $5,000+
- Recalls: None Found
Transmission
Allison 10-Speed Automatic (paired with 6.6L Duramax Diesel)
- Harsh or Erratic Shifting
- Description/Symptoms: Abrupt or jerky shifts, especially between certain gears. Can be intermittent or occur consistently. Sometimes reprogramming the TCM can address this.
- Solution: Software update/reprogramming of the Transmission Control Module (TCM). If that doesn’t work, valve body replacement or complete transmission rebuild.
- Estimated Cost to Fix: $150 (reprogram) - $6,000+ (rebuild).
- Recalls: None Found
6-Speed Automatic (paired with 6.6L Gasoline V8)
- Torque Converter Shudder
- Description/Symptoms: A shaking or vibration felt in the vehicle, especially at lower speeds or when the torque converter is locked up.
- Solution: Replacement of the torque converter or a complete transmission rebuild in severe cases.
- Estimated Cost to Fix: $1,500 - $4,000+
- Recalls: None Found
Suspension
- Front End Noise
- Description/Symptoms: Clunking or popping noises coming from the front suspension, especially when going over bumps. Can be caused by worn ball joints, tie rod ends, or stabilizer bar links.
- Solution: Replacement of the worn suspension components.
- Estimated Cost to Fix: $200 - $1,000+ per side, depending on the components needing replacement.
- Recalls: None Found
Electrical
- Infotainment System Freezing/Crashing
- Description/Symptoms: The infotainment screen freezes, becomes unresponsive, or reboots intermittently. Can be caused by software glitches or hardware issues.
- Solution: Software update (if available) or replacement of the infotainment system module.
- Estimated Cost to Fix: $0 (if software update resolves) - $1,200+ (module replacement).
- Recalls: None Found
- Backup Camera Issues
- Description/Symptoms: Backup camera not displaying an image, image flickering, or poor image quality. Can be caused by a faulty camera, wiring issues, or a problem with the infotainment system.
- Solution: Diagnosis of the camera, wiring, and infotainment system to pinpoint the issue. Replacement of the faulty component.
- Estimated Cost to Fix: $100 - $800+
- Recalls: None Found
Exterior
- Bed Bounce/Shake
- Description/Symptoms: Noticeable shaking or vibration of the truck bed, especially on rough roads. This is a common complaint with heavy-duty trucks due to the stiffness of the suspension and the separation of the bed from the cab.
- Solution: While not a true “fix,” some owners try aftermarket solutions like adding weight to the bed or using bed-to-frame mounts to dampen the vibration.
- Estimated Cost to Fix: $50 - $500+ depending on the chosen solution.
- Recalls: None Found
Interior
- Seat Heater Malfunction
- Description/Symptoms: Seat heaters not working, overheating, or only working intermittently. This can be due to a faulty heating element or a problem with the seat heater control module.
- Solution: Replacement of the heating element or control module.
- Estimated Cost to Fix: $200 - $800+
- Recalls: None Found
Summary
The 2021 GMC Sierra 2500 HD, while a capable truck, does have some reported issues. The most concerning are related to the Duramax diesel engine’s CP4 fuel pump, which can lead to very expensive repairs. Valve lifter issues on the gas engine can also be costly. Other problems, like infotainment glitches and suspension noises, are more common and less expensive to address. Potential buyers should be aware of these issues and thoroughly inspect any used Sierra 2500 HD before purchase, and consider purchasing an extended warranty.