2018 GMC Sierra 2500 Complaints

ELECTRICAL SYSTEM,ENGINE,FUEL/PROPULSION SYSTEM — Filed 05/02/2026

GM Duramax L5P diesel engine electrical connector for #4 fuel injector. This failure caused the Diesel exhaust brake, which controls downhill speed, to disengage, extreme shaking of the vehicle, emissions system warning and speed limiting. This occurred while descending a steep grade while towing a 34 feet long, 10,000 pound trailer. This is a known issue with this diesel engine and documented in GM Technical Service Bulletin 23-NA-027. Inspection and repair at a GM dealership confirmed a known issue with the #4 injector pigtail connector caused by improper wire routing and interference wit the Sound Shield and Valve Cover Heat Shield This was a sudden failure of the #4 pigtail connector with no advance warning. In addition to violent shaking of the vehicle, multiple warnings on the DIC indicating that the Diesel Brake was disengaged, the emission system had an issue, and speed would be limited.

VISIBILITY/WIPER — Filed 02/03/2025

The component that failed is the rear glass. Yes, it is available for inspection. The rear glass defogger stopped working and melted the tabs off of the glass and burned the tabs cover. The problem has been confirmed by the dealership and i was advised there is already a recall for this but apparently my vin does not fall under the recall.

ELECTRICAL SYSTEM — Filed 08/31/2022

Service Trailer Brake System Warning From time to time, this warning goes off in the vehicle and when it does, it does it constantly. When the warning is dismissed, it does it again seconds later. If it is not dismissed, it does it again seconds later. It is a persistent three ding double chiming that is not only constant, the vehicle is doing it without a trailer connected to it. The GM dealerships we have been to regarding this issue do not know how to fix it since the warning is as intermittent as it is persistent. Once one of the dealerships was finally able to observe the warning themselves, we were told because it does not cause the check engine light to come on, they are not given a code, therefore, they do not know how to address the issue. The Service Engine Brake System warning is not only a persistent auditory nuisance. The warning chime overrides any other audio capability of the vehicle and it will be the only thing the control panel shows. If the warning is dismissed, it comes right back. This means we cannot hear anything else in the vehicle, such as turn signals, and we cannot see anything else on the control panel, such as speed. We can only surmise this issue is some sort of an electrical system malfunction since we do not have a trailer connected to the vehicle when the Service Trailer Brake System warning is coming on. The vehicle has been presenting this persistent warning since we purchased it from a dealership in August of 2022 and the vehicle continues to present this persistent warning intermittently, which will last days to weeks at a time and is not corrected by the engine being turned off and restarted, no matter if the engine is shut off for minutes or days. How much time passes between the persistent Service Engine Brake System warning events can be less than one day to several months later.

FUEL SYSTEM, DIESEL — Filed 09/26/2024

The contact owns a 2018 GMC Sierra 2500. The contact stated that while driving at an undisclosed speed, the vehicle lost motive power. No warning light was illuminated. The vehicle was towed to the dealer, where it was determined that the fuel pump control module needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was opened. The failure mileage was approximately 48,000.

ENGINE,FUEL/PROPULSION SYSTEM — Filed 11/06/2023

Metal in the fuel filter and throughout the fuel system, 38 codes on the computer just in 2 weeks after a full service again at the dealer. All service has been preformed at A GMC Dealer since truck was serviced. 1. P026D - Fuel injection Quantity “A” Higher then expected 2. P06CC - cylinder 8 incorrect 3. P133F - cylinder 8 glow plug offset exceeding learning limits None stop this is happening since [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

ENGINE,FUEL/PROPULSION SYSTEM — Filed 08/01/2022

Constant issues with glow plug failures, fuel rail failure, fuel pressure failure. Truck has been in the Gmc service regarding these issues constantly for the last year with a total of five repairs and replacement of glow plugs with releaning learning new plugs and now the 6th return to the shop they’re tearing down the fuel system. Malfunction and engine light consistently come on with the same occurring problems generating from the fuel system and glow plugs. Fuel mileage is absolutely terrible and lose of power hazardous to safety!!! Gmc has issued an extended warranty for 15 years and 150,000 miles, but cant and hasn’t found a repair for vehicle and just replaces the glow plugs just so they can fail again and again!!! They need to replace everything that needs to be done and if no fix they need LEMON Law The vehicle. This is ridiculous going back to the shop every two weeks I have my truck in the shop for a month to get it back, to put it back in the shop two weeks later, to have it back in the shop for a month. Since this start 17months ago I’ve only been able to put less then 7000 miles on the vehicle because GMC constantly has the truck! The is ridiculous when you’re paying $800 a month for your payment and insurance on your vehicle that you can’t drive because the manufacturer is constantly having to repair and replace the same thing over and over again

WHEELS,UNKNOWN OR OTHER — Filed 07/23/2023

driving at 70mph, thread from tire blew.. That was in July, I went and purchased another tire from Bob King GMC Wilmington, NC. The first tire that blew was now discontinued so I purchased another Good Year . On Friday I noticed that another tire on my truck had a bubble along the threads again. It was also getting ready to blow like the first tire. I went to the dealer and they told me the tire I purchased (Good Year) was also discontinued... Please look into this matter.. They have faulty tires and this matter could have turned out with a death.. It isn't the dealers fault it is Good Year .... I have also read on line this isn't the first time people are complaining about the threads coming apart....

STEERING,ELECTRICAL SYSTEM,BACK OVER PREVENTION — Filed 08/20/2023

While braking ( after being on the highway) all dash gauges turn black, radio shuts off, AC shuts off. Service Stabilitrak light comes on when dash flashes back on. While driving AC turns off, Radio turns off same stabilitrak warning flashes, speedometer turns off. Power steer control went out while trying to turn. Truck put itself in 4 wheel drive when I turned on the trailer assist. Parking assist periodically turns itself off.

ENGINE — Filed 05/26/2023

Low coolant warning light came on. I was towing a travel trailer on a very busy roadway with no place to pull off while pulling a trailer. I had to pull over to the shoulder to check the coolant level and make sure I didn’t cause major damage to my engine by letting it overheat. While waiting to let the engine cool down, I researched and found that this is a very common issue with L5P Duramax Engines in GM trucks and it is specifically related to a faulty coolant level sensor. As it turns out, my coolant level was fine and there was no issue. The danger posed by me pulling over and waiting for well over an hour on the side of the busy backroad with my son in the truck was not a necessary one. It appears that this is a well known issue that is not being addressed by GM.

ELECTRICAL SYSTEM,EXTERIOR LIGHTING,UNKNOWN OR OTHER — Filed 01/02/2023

I have a 2018 GMC Sierra Duramax Quad-Cab and when it is connected to either my boat, stock trailer, or cargo trailer the lights and electric trailer brakes on the trailers do not work. and the chime from the "Service Trailer Brake" indicator sounds and doesn't stop until I unplug my trailer harness from my truck making it a distraction and an unsafe situation when trying to navigate through traffic(changing lanes, stopping, and other functions needed when hauling trailers). The dealership said it was a module and specified which one and so I elected to replace it myself and it wasn't the issue. I choose to do the work myself as they quoted me a price of $700.00+ to repair the problem.