GMC Sierra problems
503 owners have filed defect reports on this one. That's not a small number. No active recalls — patterns come from the complaint record.
Solid reliability overall. Common issues are concentrated in a few systems.
Worth owning if you verify the specific issues below before you buy.
- Electrical system: 50 complaints, classified severe
- Reliability score 7.0/10 — around the segment average
Our read of the federal NHTSA complaint and recall record for this exact year and model — not a substitute for a pre-purchase inspection. How we score.
Buying a used 2021 GMC Sierra? Check these first
Here's what this model is known to do — so you can inspect for it, price it in, or make the seller fix it before you sign.
What to inspect on this specific car
- engine — 213 owner reports · tends to show around 60,501 mi · ~$3,100 to fix
- powertrain — 120 owner reports · tends to show around 68,004 mi · ~$2,500 to fix
- electrical — 50 owner reports · tends to show around 32,897 mi · ~$850 to fix
- steering — 31 owner reports · tends to show around 66,000 mi · ~$700 to fix
⚠ The one to take seriously: electrical is flagged severe on this model , showing up around 32,897 mi. Inspect it closely on a test drive.
Recalls to confirm are done
Run the VIN from the listing — no active recalls on this model right now, but confirm none were opened after this car was built.
Verdict for buyers: 7.0/10 model. The priciest documented failure is engine (~$3,100) — get the seller's service records for it or inspect closely. Otherwise an average-risk used buy at a fair price.
We tell you what this model is known for and what to inspect — a vehicle-history report tells you what this exact car has been through. Smart buyers get both.
See the full pre-purchase inspection checklist →Ask anything about your 2021 GMC Sierra
A noise, a warning light, a repair quote, "should I buy this?" — get an answer grounded in this vehicle's actual NHTSA record, not generic advice.
Answers use this vehicle's NHTSA complaint & recall record — owner-reported and unverified, not a diagnosis. Verify anything safety-critical with a mechanic.
Top trouble spots 8 categories with 3+ complaints
What owners are saying recent NHTSA-filed complaints · verbatim
The Intermediate speed sensor 2 and internal transmission harness failed. The repair was to replace the internal transmission harness and intermediate speed sensor. This vehicle is a 2021 and I was told this was recalled on a 2022 only.
Faulty lifters replaced on passenger side. Had only 25000 miles on engine. GM extended warranty on thousands with this engine but not mine. Have only 28000 miles on truck and just turned 5th year so warranty is void. GM should extend warranty on all vehicles with this engine.
my truck keeps having this same issue since [XXX], always take it to team Gillman second august 26 same reason they replaced the battery but is a manufacturing defect while i am driving stops out of sudden AND THIS IS THE THIRD TIME THEY SUPPOSED TO CALL ME I HAVENT RECEIVE NO…
Traveling on interstate going at the posted speed limit and turned off the interstate onto my exit turn and vehicle engine started knocking and engine shut off oil warning light came on all while trying to stop the vehicle at the cross traffice stop sighn and ended up stopped in…
Estimate your repair exposure
Drag to your current mileage. Numbers are derived from this vehicle's complaint history.
Common questions
Is the 2021 GMC Sierra reliable?
Mostly yes. With a reliability score of 7.0 out of 10 based on 503 owner complaints filed with NHTSA, the 2021 GMC Sierra is generally a sound vehicle. The areas to watch are listed in the top problem section above — most are budget items, not deal-breakers.
Should you avoid the 2021 GMC Sierra?
The 2021 GMC Sierra is acceptable, with specific caveats. Worth owning if you verify the specific issues below before you buy. The record behind that call: Electrical system: 50 complaints, classified severe; Reliability score 7.0/10 — around the segment average. This is our read of the federal complaint and recall data — not a substitute for a pre-purchase inspection.
What should I check before buying a used 2021 GMC Sierra?
Inspect the engine first — it's the most-reported issue on this model, with 213 owner complaints filed. Typical failure occurs around 60,501 miles. Average repair cost runs about $3,100 at an independent shop. Also confirm any open recalls have been completed by running the VIN, and ask for service records covering the problem areas listed above.
Is the 2021 GMC Sierra a good used car to buy?
It scores 7.0 out of 10 on our NHTSA-based read of 503 owner complaints. The main thing to watch is engine. Typical failure occurs around 60,501 miles. Priced fairly and clean on inspection, it's a reasonable used buy. Our data covers what this model is known for — pair it with a vehicle-history report on the VIN to see what that specific car has been through.
What's the most common problem on the 2021 GMC Sierra?
Based on NHTSA records, the most-reported issue is engine, with 213 complaints filed. Typical failure occurs around 60,501 miles. Average repair cost runs about $3,100 at an independent shop.
What's the most expensive thing that goes wrong?
The engine is one of the costlier repair items. Average repair cost runs about $3,100 at an independent shop. Typical failure occurs around 60,501 miles. Catching early warning signs can sometimes extend life by 20–30,000 miles.
How do I check if my GMC Sierra has open recalls?
Paste your VIN into the decoder at the top of this page. We pull live from NHTSA, so you'll see exactly which campaigns apply to your vehicle and whether the dealer has logged the fix. Recall repairs are always free regardless of mileage or warranty status.
Is an extended warranty worth it on a 2021 GMC Sierra?
Math is straightforward: a quality service contract runs $1,800–3,500 over 3 years. With 503 complaints on file and the costliest repair averaging $3,100, one major failure more than pays for it. The catch is reading the contract — many providers exclude wear items and require pre-authorization, so cheaper plans are not always better value.