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.
The worst 2018 GMC Sierra 2500 problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
- Engine8
- Electrical7
- Fuel system6
- Lights4
- Tires3
Problems by type
Tap a problem to see which part fails, at what mileage and in which other years.
- Engine8
- Electrical7
- Fuel system6
- Lights4
- Tires3
- Transmission3
- Visibility2
- Driver assistance1
- Seat belts1
- Steering1
- Wheels1
Recalls 5
Air bags: side/window: curtain: inflator
- What is wrong
- General Motors, LLC (GM) is recalling certain 2018 Chevrolet Silverado 1500, GMC Sierra 1500, 2018-2019 Chevrolet Silverado 2500, 3500, and GMC Sierra 2500, 3500 Crew Cab trucks. The left or right-side roof-rail air bag (RRAB) inflator end cap may detach from the inflator or the inflator sidewall may rupture.
- Risk
- A separated inflator end cap or inflator rupture can allow compressed gas to escape, resulting in the end cap or other components being propelled into the vehicle, increasing the risk of injury or crash.
- Remedy
- Dealers will replace the left and right side RRAB modules, free of charge. Owner notification letters were mailed November 8, 2024. Owners may contact Chevrolet customer service at 1‑800‑222‑1020, and GMC Customer Service at 888‑988‑7267. GM's number for this recall is N242474500.
Recall number 24V756000 · Recall details
Fuel system, diesel: storage: tank assembly
- What is wrong
- General Motors, LLC (GM) is recalling certain 2017-2019 Chevrolet Silverado 2500, 3500, and GMC Sierra 2500, 3500 vehicles equipped with a dual fuel tank option. The rear fuel tank may collapse and prevent the fuel pump from transferring fuel to the front tank, resulting in an engine stall.
- Risk
- An engine stall increases the risk of a crash.
- Remedy
- Dealers will inspect the fuel tank and fuel pump module, replacing them as necessary. Dealers will also add a vent hose to the rear tank assembly. Repairs will be performed free of charge. An interim owner notification letter informing owners of the safety risk was mailed on March 15, 2023. Owner notification letters were mailed June 21, 2023. Owners may contact Chevrolet customer service at 1‑800‑222‑1020 or GMC customer service at 1‑800‑462‑8782. GM's number for this recall is N222368030.
Recall number 23V047000 · Recall details
Equipment: electrical: engine block heater
- What is wrong
- General Motors, LLC (GM) is recalling certain 2017-2019 Chevrolet Silverado 2500, 3500 and 2017-2019 GMC Sierra 2500 and 3500 vehicles equipped with a Duramax diesel 6.6 liter engine and an optional engine-block heater cord. An electrical short-circuit may occur in the engine-block heater cable or in the terminals that connect the heater cable to the block heater.
- Risk
- An electrical short-circuit can increase the risk of a fire.
- Remedy
- Dealers will replace engine block heaters and heater cords. Vehicles that have this feature disabled as a remedy to the safety condition will be contacted and offered replacement block heaters and heater cords under a separate customer satisfaction program, free of charge. GM will provide free replacement block heaters and cords under a separate customer satisfaction campaign. For vehicles previously included in recall 19V‑328, the heater cord will be replaced and rerouted, free of charge. Interim owner notifications were mailed on August 13, 2021. Owner notification letters are expected to be mailed on April 4, 2022. Customers may call GMC customer service at 1‑800‑462‑8782. GM's number for this recall is 212329840.
Recall number 21V496000 · Recall details
Engine
- What is wrong
- General Motors LLC (GM) is recalling certain 2019 Chevrolet Silverado 4500, 5500 and 6500 vehicles and 2017-2019 Chevrolet Silverado 2500 and 3500 vehicles and GMC Sierra 2500 and 3500 vehicles equipped with Duramax 6.6 liter diesel engines and an optional engine-block heater. The engine block heater cord or the terminals that connect the heater cord to the block heater may short circuit and fail.
- Risk
- A short-circuit may damage the engine components and increase the risk of fire.
- Remedy
- GM will contact owners, dealers will replace the engine block heater, free of charge. Additionally, in Chevrolet Silverado 2500 and 3500 vehicles, dealers will install a new rerouted heater cord. The recall began December 11, 2019. Owners may contact GM customer service at 1‑586‑596‑1733. GM's number for this recall is N182206310.
Recall number 19V328000 · Recall details
Seat belts: front: retractor
- What is wrong
- General Motors (GM) is recalling certain 2017-2018 Chevrolet Silverado 2500 and 3500 and GMC Sierra 2500 and 3500 trucks. The front seat belt retractor assemblies were built with the incorrect torsion bar. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 209, "Seat Belt Assemblies."
- Risk
- The seat belt retractors may not perform as intended during a crash, increasing the risk of injury.
- Remedy
- GM will notify owners, and dealers will replace both front seat belt retractor assemblies, free of charge. The recall began March 24, 2021. Owners may contact GMC customer service at 1‑888‑988‑7267 or Chevrolet customer service at 1‑800‑222‑1020. GM's numbers for this recall are 17368, 17375, and 17376.
Recall number 17V567000 · Recall details
Technical service bulletins for the 2018 GMC Sierra 2500 1,121
Bulletins tell dealers how to fix known problems. A warranty extension means the manufacturer pays for that repair for longer.
- This service bulletin provides information about GM Accessories
- Unknown or other
- Unknown or other
- This PI provides Diagnostics tips on how the LIN bus works and how to diagnosis it.
- This PI was created to help address the correct repair regarding a low coolant message on the DIC
- Unknown or other
- This PI provides information to repair the door water deflector which is not sealed properly allows water...
- This PI provides diagnostic tips for diagnosing electric trailer brakes issues.
- PI to help diagnose A/C concern
- Unknown or other
What 2018 GMC Sierra 2500 owners say
Most recent owner complaints, unedited.
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.
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.
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.
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)
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
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....
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.
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.
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.
Compare the 2018 GMC Sierra 2500
Sierra 2500 vs Ford F-250 SDSierra 2500 vs Ram 2500Sierra 2500 vs Chevrolet Silverado 2500
Other model years
1994199719981999200020012002200320042005200620072008200920102011201220132014201520162017201820192020202120222023202420252026
Questions about the 2018 GMC Sierra 2500
Is the 2018 GMC Sierra 2500 reliable?
Owners have filed 35 complaints about the 2018 GMC Sierra 2500, fewer than a typical Sierra 2500 model year.
What is the 2018 GMC Sierra 2500 year score?
The 2018 GMC Sierra 2500 scores 81 out of 100 (good). The score compares it with the other model years of the GMC Sierra 2500: 75 is a typical year, 50 means twice the usual complaints, and serious complaints and recalls lower it.
What is the most common problem with the 2018 GMC Sierra 2500?
Engine and cooling, with 8 complaints. Next is electrical (7).
How many recalls does the 2018 GMC Sierra 2500 have?
5 recalls, covering air bags, fuel system, diesel and equipment.
Was there a recall on the 2018 GMC Sierra 2500 engine?
Yes, 1 recall: 19V328000. Check your VIN to see if your car still needs the free repair.
What year does the GMC Sierra 2500 have bad engine?
The GMC Sierra 2500 model years with the most engine complaints are 2001 (29 complaints), 2004 (18 complaints) and 2005 (18 complaints).
VIN decoder
See the problems and recalls for an exact car
Buying a used 2018 GMC Sierra 2500?
Check the exact car before you pay: accidents, salvage or flood titles, odometer readings and previous owners.
Check its history