2021 GMC Sierra Problems and Top Complaints – Is Your Car A Lemon?

Steering, seats, engine, and powertrain issues among the top complaints received by the NHTSA from vehicle owners

Updated on Author: Brian Jones

Getting a job done right shouldn’t mean driving grandpa’s truck. With the 2021 GMC Sierra, customers are provided a little bit of luxury with the hard-working capability of a pickup. The automaker claims “command meets comfort” with this model, but customers aren’t impressed. This GMC appears to struggle with the steering, seats, engine and powertrain, leaving owners confused about what they have paid more for.

Click on other model year to view more problems:  2018   2019   2020

Problems with the Steering and Seats

When it comes to controlling a vehicle, steering is everything. However, it’s even more important when driving a pickup truck that’s towing or hauling heavy items. Yet, this Sierra seems to fail.

Read this NHTSA complaint. “Started vehicle everything was normal, shifted vehicle into drive, proceeded forward. While driving, vehicle’s steering seized. I was unable to move the steering wheel. It was also very difficult to stop the vehicle, brakes were not working properly. Messages came up on [the] display, reading Service Power Steering and brief message about the brakes flashed quickly on the message board. At that point, turned the vehicle off after I got it stopped, turned it back on, same messages. Still unable to turn the steering wheel, repeated this several times. Approximately for fourth time, the message cleared and the vehicle was back to normal. This occurred on a city street.”

When a vehicle becomes uncontrollable, it is scary. However, the steering is only one system that keeps this truck under control. It must also be equipped with reliable, durable tires. Yet, NHTSA Campaign Number 20V684000 shows that’s not true. This recall says certain vehicles have overcured tires installed, which might lead to a break in the sidewall, creating sudden air loss, plus belt edge separation. All of these problems increase the chance of an accident, leaving customers feeling uneasy. While the GMC Sierra might exhibit command, there’s no comfort when the threat of an accident is always looming.

One key aspect of in-vehicle comfort is the seats, but this is another part of the truck that can’t seem to live up to expectations.

Another NHTSA complaint states, “Reached for a fallen object between the driver and middle front seat and there is a razor sharp piece that took a large chunk out of the hand which caused heavy bleeding and medical supplies to stop. The vehicle was stopped and just tried to retrieve fallen object between the seats. The incredibly sharp parts need to be cut or removed from this and other similar vehicles or covered with something. It was bare metal exposed out with sharp edges that cut the right hand so badly.”

It turns out that GMC might not have enough experience working with seats and seat belt construction. NHTSA Campaign Number 20V811000 says that incorrect bolts were used to attach the seat belts to the seat. If an accident occurs, the seat belts might not restrain passengers correctly, which could lead to larger injuries. However, the problem gets even larger when looking at NHTSA Campaign Number 20V792000. This recall states that the front center seat-belt bracket might not be secured correctly, causing a failure in restraining that passenger as well. This problem is apparent in more than 600,000 vehicles, leaving many people at-risk. If GMC was in “command,” these types of defects would never occur.

2021 GMC Sierra Complaint Summary

Complaint CategoryNumber of Complaints
Electrical System
Service Brakes
Power Train
Fuel/propulsion System
Unknown Or Other
Air Bags
Exterior Lighting

Engine Problems

The engine of a truck is what creates the power needed to haul and tow. With GMC, the engine simply wasn’t created to handle all of the jobs customers have.

Here’s one example of problems from the NHTSA website. “The vehicle was bought brand new and was only driven for a week. It was in motion on the freeway when the engine started to sound noisier than usual, like that of an older truck. It was hard to notice on higher speeds on the freeway, but upon slowing down on curves, it got more obvious that something was really wrong because the noise sounded like something was loose inside the engine. There was no ‘Check Engine Light’ or any other warning lights. Upon exiting the freeway, the engine shut off completely while in motion. Fortunately, I was able to pull in a parking lot and park it safely. The engine would not start safely after that, and ‘Check Engine’ activated. The vehicle is currently being diagnosed at a dealership. Last update was that the engine was being taken apart completely because they said it’s definitely inside it.”

Who wants to drive a rugged and tough truck with a failing engine? Not most customers willing to spend money on the GMC model. Even the automaker knows how many problems this engine is causing. Service Bulletin #N202319660 discusses a broken engine valve spring that leaves the motor running rough. It can also cause the Check Engine Light to come on, create a knocking or ticking noise and lead to stalling concerns. Surely there are better ways to haul goods than with this truck. At this point, even the back of a camel would be more reliable.

Don’t be stuck with a lemon. You have legal rights to cash, return or buyback.

The law makes GMC pay legal fees.

We've fixed thousands of lemon problems. Message or call 877-795-3666 today.

Problems with the Powertrain

Working in conjunction with the engine is the transmission. This part is required to provide a smooth-shifting drive, but the GMC Sierra seems to be equipped with faulty parts.

One Edmunds user states, “Bought a 2021 AT4 with 3.0L Duramax. Ordered it and waited 4 months for it to arrive. Love the ride & engine. Had to be towed to dealer with 1,236 miles due to a “transmission module issue.” Been 3 days haven’t heard back. Think transmission might’ve blown. Wouldn’t go in reverse, would go into reverse position but wouldn’t move. Engine power was reduced & check engine light came on. The 10 speed transmission was supposed to be solid…. be cautious.”

Again, these problems are not a mystery to GMC. Service Bulletin #16NA019 discusses how the transmission leads to harsh shifts, flares and slips, making any ride less enjoyable. With all of the problems bundled together, it’s clear that the Sierra can’t provide command nor comfort.

Your Lemon Law Legal Rights

Think you have a lemon? Sit back and let the experts work out your lemon case at no cost to you. The law makes Cadillac pay legal fees. You may be able to get your lemon out of your life. Every year, auto manufacturers buy back, replace or pay cash settlements to thousands of ‘lemon’ owners like you.

Brian Jones

About the Author:

Brian Jones spent more than 30 years working as an ASE Certified Master Tech and Parts Specialist at multiple dealerships. Brian has become an authority in the industry, traveling across the country to consult for car dealerships and contributing his expertise as a writer for several major automotive publications. In his spare time, Brian enjoys working on pickup trucks, muscle cars, Jeeps and anything related to motorsports.

See more posts from Brian Jones
  • R B

    I guess I shouldn’t complain our GMC Sierra Denali had 19,700 miles on it before we heard loud pounding sounds in engine like someone was talking a hammer and hitting the engine. Our truck is only one year old and it just really goes back and forth to my hubby’s work. No big trips with it and it breaks down like it has 300,000 miles on it! Unbelievable! No dealership we’ve talked to takes any kind of compassion about our issues they have already gotten your money. Spending +67,000 for a truck that breaks down is an embarrassment for GMC. I read they even knew about their engine problems. but still sold their lemon trucks! So, long story short we will be out without a truck for 2-5 weeks! Could be longer parts are the issue always blaming COVID! They are saying strip engine all the way down and their looking at the cylinders. I honestly don’t think they know what’s wrong our truck. If we had to do it all over again the heck with GMC, and that’s saying it nicely! We are so mad!!! Same story as others GMC said, probably they would cover rental car but they have to make sure it’s under warranty!!! What??? So, my hubby has no car to get back and forth to work and GMC could care less about their customers. This is mind-blowing. We all got lemons and GMC knew their engines were garbage from the start! I saw there were other recalls on seatbelt bolts, and curved tires on our trucks and we never got one recall notice from GMC and these are huge issues that can result in injuries. Geez, this is ridiculous spending that kind of money and the truck hardly makes a year! GMC YOU SINK!

  • Ed B

    5.3 engines are garbage. There to small for heavy trucks. My 2013 silvarado blew up at 105k. New engine was 8,000. dollars. Give me a Ram Hemi anyway even with their lifter oiling issue that sometimes hits at 100k pluse

  • Matt

    2021 GMC Sierra Denali, 10k Miles, steering wheel, started to shake, check engine lights and traction control alerts came on. Same issue as all these trucks. Lifters or entire engine needs to be replaced. Buyer beware steer clear of this truck.

  • Clifton B

    We have the same problem!

  • Chris $

    2021 GMC Sierra 5.3 14,000 miles warning lights came on lot of noise, dealer says lifters have to be replaced, my concern is what caused this, will it happen again and what other kind of damage. Never heard of more than 1 lifter going bad at one time. Think its BS. Not sure what to do

  • Bill W

    I have a ‘21 Sierra Denali. Has a 5.3l with 9K miles.
    Check engine light came on so I took it to a dealer. They said it shows a misfire but it’s a software issue GM doesn’t have a fix for yet. Reset it.
    One week later light is flashing and truck running horrible. Took to closest dealer. They said a lifter collapsed. Been waiting for almost 5 weeks now with no loaner. GM is supposed to reimburse me for a rental and make my payment, but not until work is completed. Been waiting for an upgraded head gasket but they’re only replacing one.
    A $65k truck that I’m going to be worried about failing again. You buy a brand new vehicle to have a dependable ride.
    GM doesn’t care.

  • Claude H

    I bought my 2021 sierra 5.3l truck in April 2021, had 8500kms on it and a spring let go on one of the lifters, it has been at the dealer for 2 weeks waiting on parts, have not heard when the parts will arrive.
    A $60,000 truck 5 months old and problems with the engine just not acceptable, GM should replace the truck. If you pay that kind of money for a vehicle you should get a dependable machine.

  • Lucy P

    Heard a loud knocking noise and noticed heavy soot on exhaust pipes. We have a 2021 Sierra Denali, 6.2L engine with exactly 5,000 miles. It was towed to the dealereship on Monday 8/16/21. Awaiting a response as to when it will be ready. We were told the rod is bent and lifters damaged.

  • Dan

    2021 AT4 with 6.2 engine. 9100 miles. Ran ok but always had loud knocking. Started it the other day, loud banging and black exhaust smoke. Dealer told me they have to replace all lifters.

  • David M

    New 2021 GMC Sierra AT4 5.3L. 7,200 miles and broken valve spring and lifter. Dealer has had the truck for 29 days now and say it needs a complete engine replacement, but they have no idea when they will get it back to me. Only offered me a ride back to work. Had to argue for an hour and a half to get a rental car that I am paying for with the understanding that GM will reimburse me. Don’t feel comfortable about that, but have no other choice. GM has been no help. Dealer has been no help. This is a known issue on all 5.3 and 6.2L v8’s made by GM from June 1 to Oct 24 last year. They are doing very little about it.

  • Joe P

    2021 GMC Sierra, 6,400 miles and engine has a bad lifter. Engine service light did not come on until the sound got worse (two days). Truck was towed back to the dealer. Dealer had the truck over a week and truck has not been touched. I did obtain a new loaner (diesel version). We suspect the top end will be rebuilt…….

  • Anthony

    I have a 2021 GMC Sierra wi just a little over 3”11,000 miles. The dealership is not being helpful (long story there). I dropped my vehicle off and was told it would take approximately 2-weeks to have it returned. I did not receive a loaner or rental, although I was told this would be part of the deal. They did offer me a one-way Uber! I, use my truck for work and am required to have reliable transportation as a condition of employment. The dealership could care less, however, I did get a LOT of “I understands” after having to speak to multiple employees.

  • Eric H

    New 2021 GMC Sierra 5.3L dealer is already going to take engine apart replacing lifters,push rods head gaskets almost a full overhaul and only had truck for about 3 months second time at service department been almost 1 week at dealership the second time only has 6,030 miles there willing to trade the vehicle back but now I’m upside down almost 10 thousand I went in to get this vehicle with a trade at positive 5 thousand not fair for me to go negative equity on a truck that broke who wants to continue paying for a plus 50K truck with a rebuilt engine. There telling me these defective engine parts were not heat treated correctly from the factory plant due to Covid shutting plant ovens down it’s not my fault I told them.

Leave a Reply or Comment

Write a comment below to share online. Or, instead you can to our legal team.

Please select your star rating.

Briefly describe your experience Briefly describe your experience

What’s your name? What’s your name?

What’s your phone number? Please enter a valid phone number

Want to know if you could sue? Get a free legal evaluation from Lemberg Law?

Get Your No-Obligation
Case Evaluation

Send a secure message to our legal team.

What’s your name? What’s your name?
What’s your email address? What’s your email address?
What’s your phone number? What’s your phone number?
Briefly describe the problem Briefly describe the problem
Confidentiality Guarantee: We keep your information completely confidential and will not send you spam or sell your information.
By submitting above, I agree to the privacy policy and terms and consent to be contacted by an agent via phone call or text message at the phone number(s) listed above, including wireless number(s).