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GMC Sierra 3500Model year report

2020 GMC Sierra 3500 Problems

Compared with other GMC Sierra 3500 years

More complaints than typical for this model

95/100 2.8× a typical year · 50 = typical

Nearby years with a typical complaint level and no open NHTSA investigation: 2022, 2023

Based only on NHTSA complaints, recalls and investigations. Not adjusted for how many vehicles were sold, and not a reliability rating. How this is calculated

Complaints
51filed with NHTSA
Median mileage
28,700miles, 10 complaints with mileage
Recalls
8campaigns on record
Trend
RisingComplaints filed in the last 3 full calendar years are at least 25% higher than in the 3 years before.

Sources: NHTSA records for the 2020 GMC Sierra 3500 (complaints, recalls, investigations). Report an error

What owners report

Owners of this model year most often describe sudden rear wheel lockup or skidding, followed by sudden power loss or limp mode, and many complaints do not list mileage. Related recalls describe a transmission control valve that may fail and cause the rear wheels to lock up, and towing is a recurring setting across these complaints.

  1. Transmission and drivetrain

    Sudden rear wheel lockup or skidding

    • 10 complaints (20%)
    • typically at 4.8 yrs old
    • 2 mention a crash, fire or injury
    • filed 2023–2026

    Owners describe the rear wheels or brakes locking briefly, often with a loud bang, followed by a skid, and sometimes smoke or flat-spotted tires. Some report the lockup happening again within seconds or minutes, and the dealer often could not reproduce it. According to complaints, the recall repair was not available or did not stop the problem in some cases, and a dealer planned to replace the transmission valve body. Mileage is not listed in these complaints, which describe speeds of about 45 to 65 mph, with some occurring while towing a trailer.

    Recall 24V797000Recall 26V0830001 related service bulletin

    What to check: Check the VIN for open recalls, especially the transmission control valve recalls, and ask whether the control module software repair was done. Ask the seller for any records of transmission valve body or control module work.

    2 excerpts from owner complaints in NHTSA records

    “I was driving approximately 60mph pulling a trailer when the back tires locked up for approximately 2 seconds. This happened 3 times within 30 minutes. I've taken it to the GM repair shop. They have seen this happen to 3 or 4 vehicles. Due to not being able to replicate the fault it has been difficult to diagnose. They are going to replace the transmission valve body hoping that will take care of the issue. This is extremely dangerous to everyone on the road when this happens. …”

    NHTSA complaint #11585881, filed 2024-04

    “driving 45 mph westbound i70 at eisenhower tunnel, vefhicle made loud bang, brakes locked up momentarily slowing vehicle to around 25mph. multiple vehicles had to make evasive manuevers to avoid collision. vehicle released after a 15FT skid. pulled over to safety and inspect for damage, tires were falt spotted but no damage was visible. called dealer servcei and was told to make appt and set for diagnostic. service could not replicate or find damage so I was sent on my way and told if it does it again let us know. …”

    NHTSA complaint #11598426, filed 2024-07
  2. Engine

    Sudden power loss or limp mode while driving

    • 11 complaints (22%)
    • median 68,000 mi at 5.1 yrs old (4 state mileage, few)
    • 1 mention a crash, fire or injury
    • filed 2021–2026

    Owners describe sudden speed reduction or power loss, sometimes entering limp mode with no warning light, and in some cases the engine shutting off and failing to restart. In some complaints the power loss is tied to a transmission valve body sensor, a diesel exhaust fluid heater problem that reduces engine power, or an engine that seized. According to complaints, some vehicles were not repaired at the dealer visit, and the manufacturer referred an owner to the NHTSA hotline. Mileage is listed from about 19,000 to 130,000 miles, and some complaints describe it happening at highway speed.

    2 related service bulletins

    What to check: Ask whether the transmission control valve service campaign or a front pump leak check has been completed, and look for stored codes after any power loss. On a test drive, watch for sudden loss of power or limp mode when accelerating from a stop.

    2 excerpts from owner complaints in NHTSA records

    “the engine seized at 65mph. available for inspection. was left stranded in a limited access area with no cell service. there was no warning, the engine just stopped at highway speed and would not restart. the problem was confirmed by an independent service center. they couldnt identify which component had failed without a costly teardown. occurred at 112,000 miles, past the 100,000 mile powertrain warranty.”

    NHTSA complaint #11691992, filed 2025-10

    “The contact owns a 2020 GMC Sierra 3500. The contact stated while driving approximately 60 MPH, the vehicle jerked, lost motive power, and almost stopped unintendedly. There was no warning light illuminated. The contact was able to pull into a parking lot, where the vehicle shut off. The contact stated that while attempting to restart the vehicle, the diagnostic trouble code: P129F was displayed, and the vehicle failed to restart. The vehicle was towed to the residence. …”

    NHTSA complaint #11627460, filed 2024-11, 19,000 miles
  3. Brakes

    Dash warning cuts power and trailer brakes

    Mentioned in 4 of 46 sampled complaints

    Owners describe the dashboard warning lighting up and the computer cutting engine power, which also takes the trailer brakes offline. Complaints say the warning often appears with little or no lead time, and a complaint describes the trailer brakes failing when the truck shut off. According to complaints, the dealer has worked on the problem repeatedly, and open cases with the manufacturer have had no resolution. Mileage is not listed in most of these complaints, but a complaint's text says the problem was present at 600 miles and that the truck had about 75,000 miles.

    What to check: Ask for dealer repair records for any dash warning or trailer brake problem, and check whether the system has any stored codes. A test drive with a trailer, if possible, can show whether the warning appears under load.

    2 excerpts from owner complaints in NHTSA records

    “The computer malfunctions. It is available for inspection. The computer lights up and causes failure in the trailer brakes. Glenn Polk the dealership in Sanger Texas has been working on a fix but has yet to come up with one. I have spoken with General Motors Representatives several time trying to resolve the problem without result. I also emailed the CEO last Friday and have heard nothing. There were no warning lights until seconds before failure.”

    NHTSA complaint #11418543, filed 2021-05

    “The computer lights up the dash reducing power and turning off power to trailer brakes. This has almost caused an accident on several occasions . It happens a couple of times per trips. This vehicle has been in the shop a couple of times per month since it was put into service. Glenn Polk Chevrolet has worked on it each time and the problem is still there. This truck has also had several injector issues. There is an open case with this vehicle with General Motors with no resolution. I have filled out forms on each of my 2020 GMC's 3500's.”

    NHTSA complaint #11418621, filed 2021-05
  4. Tires

    Tire tread separation or blowout

    • 5 complaints (10%)
    • median 29,400 mi at 3.6 yrs old (1 states mileage, few)
    • filed 2022–2025

    Owners describe the tread separating from original factory-installed all-terrain tires, sometimes with a sudden loss of pressure or a rear blowout. According to complaints, the tire pressure monitor showed normal readings just before a failure, and in one case the dealer found tread separation on a front tire and bubbles on a rear tire. Where mileage is listed it is about 21,000 to 29,400 miles, and most failures occurred at highway speeds, often while towing.

    What to check: Check the tread on all tires for separation, bubbles, or uneven wear, and ask whether any tire recall or replacement applies to the VIN. Ask the seller about the tire age and any past tire failures, especially if the truck is used for towing.

    2 excerpts from owner complaints in NHTSA records

    “I had a blow out on my rear tire on my 2020 GMC Sierra 3500 AT4 truck while travelling down the highway while pulling my 43 foot RV fifth wheel toy hauler. The vehicle had 21,000 miles on it. The tires and wheels are Goodyear Wrangler LT275/65R20 E rated tires. The problem is i changed the tire to find i had a a MICHEllin LT 275/70R18 tire for a spare that i changed. This effected the ABS and was hard pulling my RV back home for another 40 miles. …”

    NHTSA complaint #11486937, filed 2022-09

    “Goodyear Wrangler Trailrunner AT, LT275/65R20, factory installed on a 2020 GMC Sierra Denali 3500. While traveling 60 mph pulling a fifth wheel in South Texas on a clear and dry day, the rear passenger tire unexpectedly lost its tread. As we slowed down, it completely lost tire pressure and we ran on the rim until coming to a complete stop. Immediately prior to the incident, the TPMS and other safety systems in the truck read normal. There were no system warnings and no objects in the road. …”

    NHTSA complaint #11495345, filed 2022-11

Buying note. Buyers considering this model year may want to check the VIN for open transmission control valve recalls and ask for records showing the control module software repair was done. If the truck will be used for towing, a test drive with a trailer can show whether any dash warnings or trailer brake issues appear under load.

Summary written with AI from a sample of 46 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.

NHTSA recorded 51 consumer complaints for the 2020 GMC Sierra 3500. 10 of the complaints include a mileage, and 70% of those were filed for vehicles with under 50,000 miles; the median is 28,700 miles. Of all complaints, 4 involved a crash, 2 a fire, 4 an injury, according to the filers. NHTSA lists 8 recall campaigns and 906 technical service bulletins for this model year. Compared with the other 4 GMC Sierra 3500 model years that have at least 25 complaints and are old enough to compare, this one scores 95 out of 100, where 50 is a typical year for the model (more complaints than typical for this model). The comparison allows for the era and for how long each year has had to collect complaints, but not for how many vehicles were sold.

Which parts are reported most

Complaints can name more than one part, so the counts add up to more than the total. Select a part to see its complaints, recalls and bulletins.

Also reported: Engine cooling (1), Exterior lighting (1), Forward collision avoidance (1), Lane departure (1), Latches, locks and linkages (1), Steering (1), Wheels (1).

Example complaints

Transmission and drivetrain: “driving 65mph on interstate, attempted to change lanes to pass slower vehicle and pressed upon accelerator pedal...truck violently skidded to a stop and sent me onto shoulder, many vehicles behind me swerved to avoid my vehicle. GM wont repair and says since they cant replicate its not really happening. this has happened twice in last 2 weeks.”

NHTSA complaint #11602485, filed 2024-07

Electrical system: “The component that failed was the passenger side or main battery. Our safety was compromised when the design of the HVAC system and the battery location allowed the hydrogen sulfide gas into the passenger compartment of the vehicle. The issue has not been confirmed by a deal or independent service center. The battery(s) and vehicle are available for inspection to confirm the issue. I have uploaded pictures of the battery and one can visually see the swollen battery with liquid leaking out of it. There were no warning messages or other symptoms prior to the failure. …”

NHTSA complaint #11471359, filed 2022-06

Brakes: “driving approximately 50 mph when vehicle suddenly made loud bang and locked up rear brakes for 25' coming to a stop in road side ditch, numerous vehicles had to make evasive actions to avoid me and other vehicles. flat spotted tire abut no visible physical damage. sat on side of road for transmission temp to cool down then drove to shop without repeat. called dealer was told the earliest appt was a month away. have not been able to repeat incident so far. …”

NHTSA complaint #11598428, filed 2024-07

Mileage when problems were reported

70% of the 10 complaints with a mileage were filed for vehicles with under 50,000 miles; the middle half falls between 19,000 and 50,000 miles.

20%0–1020%10–2530%25–5010%50–750%75–10020%100–1500%150+
Share of complaints by mileage when the problem was reported, in thousands of miles (10 complaints with mileage). Red bars: under 50,000 miles. Bucket widths differ. Median: 28,700 miles.

Complaints by year filed

Trend: rising. Complaints filed in the last 3 full calendar years are at least 25% higher than in the 3 years before.

2019202020212022202320242025152026
Complaints by year the complaint was filed with NHTSA. Red bars: the last 3 full calendar years used for the trend. The current year (2026) is partial.

Recalls and investigations

See all 8 recalls for the 2020 GMC Sierra 3500 → · Check a VIN at nhtsa.gov/recalls

Technical service bulletins

TSBs are manufacturer notes to dealers about known repair procedures. They are not recalls and do not by themselves mean a vehicle has a fault. 906 on record; the latest 10 are shown.

See all 906 bulletins →

Other model years of the GMC Sierra 3500

YearComplaintsMedian miRecallsCrash ★MPGScore (50 = typical)Trend
202652,2502———Too new
20251740,0001———Too new
20245036,0003——Too new to compareToo new
20232833,8001——47 · TypicalToo new
20223231,1543——54 · TypicalRising
202120101,5005———Rising
20205128,7008——95 · MoreRising
20191353,0047———Not enough data
20181453,8006———Not enough data
20171321,0007———Not enough data
20161927,5007———Rising
20153138,5007——50 · TypicalFalling
2014768,0003———Not enough data
20131449,2184———Not enough data
2012931,2004———Not enough data
20112077,2505———Falling
2009536,6005———Not enough data
20082559,0003——0 · FewerFalling
20071636,0003———Rising
20061149,9740———Not enough data
20052450,5000———Rising
20042484,0000———Rising
2003760,5000———Not enough data
20022079,0002———Stable
20013663,5402——Not compared (before 2008)Falling
20002657,0072——Not compared (before 2008)Rising
19991959,5001———Stable
199812128,0002———Not enough data
19971095,0001———Not enough data

All GMC Sierra 3500 model years · Best and worst years by complaints

Frequently asked questions

What are the most common problems with the 2020 GMC Sierra 3500?

Owners of this model year most often describe sudden rear wheel lockup or skidding, followed by sudden power loss or limp mode, and many complaints do not list mileage. The issues reported most often: Sudden rear wheel lockup or skidding; Sudden power loss or limp mode while driving; Dash warning cuts power and trailer brakes.

How many NHTSA complaints does the 2020 GMC Sierra 3500 have?

NHTSA recorded 51 consumer complaints for the 2020 GMC Sierra 3500 as of Oct 27, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.

What part of the 2020 GMC Sierra 3500 is reported most often?

Transmission and drivetrain is named most often, in 19 complaints (37% of the total), followed by electrical system with 9.

Has the 2020 GMC Sierra 3500 been recalled?

NHTSA lists 8 recall campaigns for this model year. To check a specific vehicle, enter its VIN at nhtsa.gov/recalls.

At what mileage are problems with the 2020 GMC Sierra 3500 reported?

Among the 10 complaints that include a mileage, the median is 28,700 miles and the middle half falls between 19,000 and 50,000 miles; 70% were filed for vehicles with under 50,000 miles.

About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 27, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.

Complaint counts come from NHTSA’s public complaint database; we count each complaint once. The source records for this vehicle are on nhtsa.gov. Scores and trends are our own summaries of that data, described in the methodology. This page is not legal, safety or repair advice: for a specific vehicle, check its VIN at nhtsa.gov/recalls and ask a qualified mechanic. See an error? Tell us.