2020 GMC Sierra 1500 Problems and Top Complaints – Is Your Car A Lemon?

Fuel system, brakes, electrical and engine issues among the top complaints received by the NHTSA from vehicle owners

Updated on Author: Brian Jones

While the 2020 GMC Sierra 1500 isn’t the most popular among the pickup segment, it is considered a higher-end model. Even the automaker claims it provides “details with distinction.” However, customers expect more for the money that is spent. What they aren’t looking for is the defective electrical system, malfunctioning fuel system, poorly-made structure, failing service brakes and dangerous engine like they have received.

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

Problems with the Electrical System

A luxury truck such as the Sierra should be equipped with the latest bells and whistles. Plus, everything should work the way it was designed, but that’s not the case.

Take a look at this Edmunds review. “GM has removed their built in messaging app so the only way to receive text messages through their system is to plug in / tether your phone and use Apple Car Play or AA. One can send text messages using voice commands but not receive, or even be notified of incoming messages when connected via Bluetooth. Their system also turns the volume down on the phones which causes problems. Many pages of information / complaints regarding these issues are available by doing a search.”

Even more serious than this is the recall related to the electrical system. NHTSA Campaign Number 19V888000 says that 350,000 vehicles might have a battery positive cable ring that was manufactured with too much glue. Because of this, there is an intermittent electrical connection between the cable and alternator. Not only can this cause the truck to stall and create an accident, but it could also produce electrical arcing, which could start a fire. Considering the term “distinction” means “excellence that sets something apart from others,” it’s clear that the Sierra 1500 deserves that title as most trucks are not randomly starting on fire.

2020 GMC Sierra 1500 Complaint Summary

Complaint Category Number of Complaints
Electrical System
Service Brakes
Unknown Or Other
Power Train
Fuel/propulsion System

Electrical System complaint logged with the NHTSA

Brand new truck. Stuck at the gym in the middle of the night truck wont start. The interior lights, head lights, and radio wont shut off. Vehicle wont start. I’m assuming the battery was drained because interior lights, exterior lights, radio, wont shut off. Has to be some kind of electrical malfunction. Waiting on GM roadside.

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Problems with the Fuel System

Looking at the fuel system, we see many more defects that are just as scary.

Here is one NHTSA complaint. “Smell of smoke strong in the cab and outside hood of truck. Also have seen smoke coming from hood of truck. Smells like burning electrical or plastic.”

Here’s another owner that worries about a truck fire, and this person has every right to think that way. Even NHTSA Campaign Number #19V837000 states that the fuel pump might have been installed without a pressure regulator, which allows over-pressurization of the system. If this happens, the fuel pump could crack and begin leaking. Of course, when ignited, this might also lead to a truck fire. Basically, there should be a large “flammable” warning written on every side of the truck to ensure no one dies in a fire.

Vehicle Structural Problems

It seems that GMC put just as much thought into building the structure as they did creating the essential components.

Another Edmunds review states, “I bought a 2020 GMC Sierra 1500 pickup and the bed assembly is crooked. The dealer told me ‘they are all that way’ and ‘no one ever notices’ and “if they do they just live with it… This is a joke….buyer beware.

Additionally, there is a defect with the structure that leads to another recall. NHTSA Campaign Number 19V814000 states that over 550,000 vehicles have an opening in the seat belt pretensioner bracket that could allow a fire to reach the carpet. Of course, in most vehicles, the chance of fire is so low, this might not be a big deal. But, as shown before, that’s not the case with the GMC Sierra 1500. In fact, this truck is considered a fireball waiting to happen.

Problems with the Service Brakes

The brakes of a truck are set up to stop it before a collision occurs, but this is just one more system that disappoints owners.

One NHTSA complaint says, “The ABS system failed while driving down the road, causing the brakes to lock up and caused the truck to spin out of control nearly crashing into another vehicle and jumping over the center divide into oncoming traffic.”

Again, there’s another recall worth mentioning. NHTSA Campaign Number 20V116000 states that the bolts used to attach brake calipers might not have been heat treated. When this happens, either the front or rear brake calipers could break if put under a load. Considering this is a full-size truck, it’s likely that owners are putting a load in the bed, unaware of this possible defect. So, whether the brakes fail or the truck combusts, the Sierra isn’t good for much else other than becoming a front lawn ornament.

Brake problem complaints logged with the NHTSA

TL* the contact owns a 2020 gmc Sierra. The contact stated that while driving at 25 mph, the system brake failure warning message illuminated on the instrument panel. Once the warning light illuminated, the contact experienced complete brake and steering failure. The contact was able to steer the vehicle into a curb to slow down the vehicle and avoid a possible collision with another vehicle. The contact stated that he had suffered pain to his left shoulder blade and left knee; However, he did not seek medical attention due to COVID-19. After experiencing the failure, the contact had the vehicle towed to dealer where they cleared the system’s computer and informed the contact that they found no defects with the vehicle. Upon return of the vehicle, he experienced another brake failure as the check engine light illuminated while driving at 55 mph. Due to the failure, the contact was forced to run a red light and drive up an incline in order to bring the vehicle to a complete stop. The vehicle was then towed another dealer where it remained in their possession. The manufacturer was notified of the failure and a field inspector was sent to inspect the vehicle. The contact stated that know brake failure codes were detected. The contact stated after the third failure the vehicle was towed again to dealer where it was awaiting diagnosis. The vehicle had yet to be repaired. The failure mileage was unknown.

Engine problems

From a purely mechanical standpoint, the engine in this truck must be powerful and dependable to haul heavy loads (when the brake calipers aren’t broken). Yet, this engine is just one big disappointment.

A final NHTSA review says, “Engine Light keeps coming on. Code reading the knock sensor needs to be repaired. Sensor has been replaced twice in the past three months.”

Service Bulletin #140604004G also talks about how the engine can make strange noises, but this is “completely normal” if the temperature outside is cold or the truck has been sitting for several hours. There are very few instances when a new truck engine should be making strange sounds, but GMC is working to portray something false to owners. Apparently, it is too much to admit to one more failure with this pickup

Engine problem complaints logged with the NHTSA

Engine like keeps coming on. Code reading the knock sensor needs to be repair. Sensor has been replace twice in the past three months.

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 GMC 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.

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
  • Sarah M

    My transmission has had a whining noise since I purchased it from Carvana, they said it was normal. Now my 2020 GMC Sierra 1500 Texas Edition has had engine problems since 12/29/23, also the transmission has to be replaced. The 1st thing that happened is something that broke on my front driver tire side, it dropped my truck front end down and ruined my tire and rim. 6/23

  • woodrow m

    Transmission is harsh shifting on cold start, 1st and 2nd shifts. GM says no fix for problem.

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