2020 Gmc SIERRA 3500

Problems, Recalls & Reliability Report

Average

Quick Summary

The 2020 Gmc SIERRA 3500 has 72 owner complaints filed with NHTSA — that's 0.9x the segment average of 80. The most common issue is transmission problems (26% of all complaints), specifically: the computer lite up the dash and reduced power, plus took the trailer brakes off line. this happened while loaded. to reset the system you have to pull over and turn the vehicle off. this happens 2-3 times per day. this was a problem at 600 miles. the transmission shifted from 10 gear to 5th g. ⚠️ 4 fire reports filed.

4 fire reports 5 crash reports 4 injuries

Total Complaints

Recalls Issued

—/5

Safety Stars

0.9x

vs Segment Avg

Known Problems

TRANSMISSION

19 complaints

26%

• The computer lite up the dash and reduced power, plus took the trailer brakes off line. This happened while loaded. To reset the system you have to pull over and turn the vehicle off. This happens 2-3 times per day. This was a problem at 600 miles. The transmission shifted from 10 gear to 5th g
• The exhaust system is directed to the rear of the vehicle and when towing causes extreme heat to build on the item being towed, in my case a 5th wheel camper. The heat has melted the trim on my camper and is a potential fire hazard.
• Rear tires locking up out of no where almost made me jack knife.

Typical onset: 50K miles Est. repair: $500💥 3 crashes

“The computer lite up the dash and reduced power, plus took the trailer brakes off line. This happened while loaded. To reset the system you have to pull over and turn the vehicle off. This happens 2-3 times per day. This was a problem at 600 miles. The transmission shifted from 10 gear to 5th g”

— NHTSA complaint filing

ELECTRICAL

9 complaints

13%

• PROGRESSIVE PAUSE STARTS WHEN STARTING VEHICLE. AFTER A FEW WEEKS OF PAUSE STARTING VEHICLE HAD NO POWER AT ALL. TOWED IT TO DEALER THEY REPLACED A BAD BATTERY. PAUSE START CONTINUED AND AFTER 4-5 WEEKS VEHICLE WOULD NOT START. COULDN'T TURN PARK BREAK OFF. THERE WAS POWER (LIGHTS IN DASH CAME
• 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
• The computer lite up the dash and reduced power, plus took the trailer brakes off line. This happened while loaded. To reset the system you have to pull over and turn the vehicle off. This happens 2-3 times per day. This was a problem at 600 miles. The transmission shifted from 10 gear to 5th g

Typical onset: 50K miles Est. repair: $500🔥 1 fire reports

“PROGRESSIVE PAUSE STARTS WHEN STARTING VEHICLE. AFTER A FEW WEEKS OF PAUSE STARTING VEHICLE HAD NO POWER AT ALL. TOWED IT TO DEALER THEY REPLACED A BAD BATTERY. PAUSE START CONTINUED AND AFTER 4-5 WEEKS VEHICLE WOULD NOT START. COULDN'T TURN PARK BREAK OFF. THERE WAS POWER (LIGHTS IN DASH CAME ”

— NHTSA complaint filing

BRAKES

7 complaints

10%

• 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
• The computer lite up the dash and reduced power, plus took the trailer brakes off line. This happened while loaded. To reset the system you have to pull over and turn the vehicle off. This happens 2-3 times per day. This was a problem at 600 miles. The transmission shifted from 10 gear to 5th g
• The computer lights up dash reducing power and taking the trailer brakes away. This almost caused a wreck when the truck shut off and the brakes failed. This truck has been in the shop at least once per month trying to fix the issues, from computer and brake failure to injector failure. Glenn Po

Typical onset: 50K miles Est. repair: $500💥 1 crashes

“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 ”

— NHTSA complaint filing

ENGINE

7 complaints

10%

• 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 Chevr
• Plugged in engine block heater and the car erupted in flames. Total loss.
• 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 sta

Typical onset: 50K miles Est. repair: $500🔥 1 fire reports

“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 Chevr”

— NHTSA complaint filing

OTHER

6 complaints

• WHILE TOWING A FIFTH WHEEL CAMPER, THE EXHAUST WAS SO HOT IT MELTED THE CAMPER DIRECTLY BEHIND IT. WAS CAUGHT IN SIDE MIRROR BEFORE ANYTHING CAUGHT ON FIRE.
• In short, the Diesel Exhaust Fluid (DEF) reductant heater failed which requires the entire DEF tank assembly (part 85138746) to be replaced on my 2020 GMC Sierra 3500. This cause the truck to go into "limp" mode where it will not travel above 65 mph, and after another period, the speed continues to
• 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 transmiss

Typical onset: 50K miles Est. repair: $500🔥 1 fire reports💥 1 crashes

“WHILE TOWING A FIFTH WHEEL CAMPER, THE EXHAUST WAS SO HOT IT MELTED THE CAMPER DIRECTLY BEHIND IT. WAS CAUGHT IN SIDE MIRROR BEFORE ANYTHING CAUGHT ON FIRE.”

— NHTSA complaint filing

Estimated Repair Costs

TRANSMISSION(~50K mi)

$500

ELECTRICAL(~50K mi)

$500

BRAKES(~50K mi)

$500

ENGINE(~50K mi)

$500

OTHER(~50K mi)

$500

Estimates based on average reported repair costs. Actual costs vary by location, shop, and severity.

🔍 Pre-Purchase Inspection Checklist

Based on 72 owner complaints for this specific year, here's what to check or ask about:

☐
TRANSMISSION: The computer lite up the dash and reduced power, plus took the trailer brakes off line. This happened while loaded. To reset the system you have to pull over and turn the vehicle off. This happens 2-3 times per day. This was a problem at 600 miles. The transmission shifted from 10 gear to 5th g
Typically appears around 50K miles. Repair cost ~$500
☐
ELECTRICAL: PROGRESSIVE PAUSE STARTS WHEN STARTING VEHICLE. AFTER A FEW WEEKS OF PAUSE STARTING VEHICLE HAD NO POWER AT ALL. TOWED IT TO DEALER THEY REPLACED A BAD BATTERY. PAUSE START CONTINUED AND AFTER 4-5 WEEKS VEHICLE WOULD NOT START. COULDN'T TURN PARK BREAK OFF. THERE WAS POWER (LIGHTS IN DASH CAME
Typically appears around 50K miles. Repair cost ~$500
☐
BRAKES: 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
Typically appears around 50K miles. Repair cost ~$500
☐
ENGINE: 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 Chevr
Typically appears around 50K miles. Repair cost ~$500
☐
General: Get a pre-purchase inspection from an independent mechanic ($100-$200)