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The Mercedes-Benz GLS SUVs are lightweight (leicht), cross-country vehicles (gelandewagen). That’s where the G and L come from. The S stands for special class (sonderklasse).
The GLS has been around since 2006 when it joined the Mercedes-Benz lineup as the brand’s first 7-passenger SUV. A highlight of the second generation was its innovative engine start/stop system, called ECO-START. The third generation, introduced in 2020 offered two powerful engine options and a bunch of new features.
Click on other model year to view more problems: 2021
Contents
- 1| NHTSA Complaints for the 2020 Mercedes Benz GLS
- 2| The Most Common Problems with the 2020 Mercedes Benz GLS
- 3| 2020 Mercedes Benz GLS 48V Battery Problems
- 4| 2020 Mercedes Benz GLS Engine Problems
- 5| 2020 Mercedes Benz GLS Fuel/Propulsion Problems
- 6| What to do if Your 2020 Mercedes Benz GLS is a Lemon? Your Lemon Rights
- 7| Complaint Data
Don’t be stuck with a lemon. You have legal rights to cash, return or buyback.
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NHTSA Complaints for the 2020 Mercedes Benz GLS
| Complaint Category | Number of Complaints |
|---|---|
| Electrical System | |
| Fuel/propulsion System | |
| Engine | |
| Power Train | |
| Unknown Or Other | |
| Steering | |
| Seats |
But complaints about the 2020 GLS-Class SUV are mounting up. There are currently 11 complaints to the U.S. Department of Transportation’s National Highway Traffic Safety Administration (NHTSA). Of these, 7 are listed as electrical system problems and 6 as fuel/propulsion system issues. A total of 4 are seen as engine problems and there are also 2 complaints about the powertrain. There is 1 complaint each about seats, steering, and another listed in the Unknown or Other category.
The Most Common Problems with the 2020 Mercedes Benz GLS
The most common problem with the 2020 Mercedes-Benz GLS-Class SUV is its 48-volt batteries.
2020 Mercedes Benz GLS 48V Battery Problems
Nearly half the complaints to NHTSA relate to battery problems
Lemberg Law is currently investigating complaints about Mercedes-Benz GLE battery problems. From complaints we have identified about other models, it might be a much broader issue. For example, we are aware that there are at least three technical service bulletins (TSBs) that Mercedes-Benz has issued about the 48V battery problems, but only one is officially linked to the 2020 GLS. This states that the cause might be software or hardware issues.
Battery Issue is a life-threatening problem
The owner of a GLS SUV with a battery issue believes it is “a LIFE-THREATENING DANGEROUS VEHICLE PROBLEM,” especially because the problems keep recurring.
The first time, the engine turned off and the car wouldn’t accelerate. Once this happened on a busy freeway.
“In this instance, the 48-volt battery failure warning, engine overheat warning, engine light warning came on. When MCB dealership evaluated the vehicle, there were no stored associated error codes and MCB service returned the vehicle to me saying that the issue did not occur when they drove it.
“The same issue occurred again 5 months later, this time in a busy intersection, where the car would not accelerate and I was forced to pull off the road. The check engine light as well as other failure lights came on. The car was returned to MCB service and again, no error codes were stored and the dealership said they could not find the cause of the problem.”
This owner is convinced the problem “could easily result in a catastrophic accident.” Additionally, “Mercedes is taking no accountability for this vehicle failure and claims they have not heard of this issue prior, which is clearly inaccurate given that it has been reported to NHTSA by several other GLS owners.”
Other similar complaints echo how dangerous the issue is
“In looking at the issue online this appears to be a known problem to Mercedes. They are even facing a class action lawsuit for it in the same model year GLE, which is based on many of the same systems. Someone is going to get killed when their vehicle stalls in the middle of the highway.”
After being told there was a 48V battery malfunction, another owner was warned not to drive the vehicle “under any circumstances.”
“This is a serious issue and it appears that changing the battery does not correct the issue.”
An owner who shipped a new 2020 Mercedes-Benz 450 from Oakland to Hawaii complains that the failure happened about 4,100 miles. “We experienced a 48 volt battery malfunction which left our car disabled on the side of an uphill major roadway. There was no warning, just a sudden extreme loss of power. Supplemental systems such as the AC deactivated. Warning lights flashed and our vehicle coasted to the side of the road.”
The owner wasn’t able to accelerate and there were over-heating warnings in red.
“We are very concerned (that) this malfunction is a safety-related issue and needs to be escalated. Sudden unexpected loss of power creates extremely dangerous situations.”
2020 Mercedes Benz GLS Engine Problems
Engine problems relate to the engine dying or shutting off.
An owner from Virginia has found that “on numerous occasions, when either slowing down or in a slow turn, the engine dies and will not reengage until I have turned off the vehicle, exited, then reentered and started the vehicle.’
Offering passengers as witnesses, the owner says the SUV was “almost broadsided when the vehicle stopped in the middle of a left-hand turn, crossing three lanes of oncoming traffic. The vehicle has been to the dealership at least three times and it’s either a ‘software update’ requirement or ‘we can’t duplicate’ the issue.”
However, the owner was also told by someone in customer services, “I have seen this issue before.”
2020 Mercedes Benz GLS Fuel/Propulsion Problems
Some of the fuel/propulsion complaints are linked to battery problems. But one quite different one relates to the catalytic converter. First, the owner noticed fuel odors and then abnormal noises that sounded like explosions. At this point, the dealer diagnosed the problem and said the catalytic converter and turbo had to be replaced. The failure mileage was only 1,000.
What to do if Your 2020 Mercedes Benz GLS is a Lemon? Your Lemon Rights
When problems recur or affect the use, value, or safety of your vehicle, there’s a possibility that you’re sitting with a lemon. But you don’t have to live with it. If you think you may have a lemon, why not let Lemberg Law assess your case.
We have negotiated numerous settlement deals for our clients and initiated many class-action suits. It won’t cost you anything because legally, Mercedes-Benz must pay all the legal fees of lemon law cases.
Complaint Data
| Category | Electrical System, Engine, Power Train |
| Date | Sep 23, 2022 |
| State | CA |
| Description | This incident occurred around 5:50pm on wednesday, september 21, 2022. I was driving on a merge connector between two freeways in san francisco at about 60mph, when the vehicle threw a series of error codes and warnings on its displays, culminating with “shut down engine immediatelyâ€. The first error was a 48v battery system charging failure, and the second was a warning that coolant was too hot. The instrument panel and steering and brakes did not lose power, but the accelerator no longer worked, and the vehicle slowed down to about 35mph. I had to merge across 4-5 lanes of rush hour traffic at this speed (sketchy) to make it to the side of the freeway, and was able to exit safely and stop in a safe spot. Upon turning off the vehicle for a few minutes and then restarting it, a generic check engine light remained on afterwards. I had the vehicle towed to a mercedes dealer where the fault(s) are currently being diagnosed. According to the dealer, they are in touch with mbusa engineering due to the nature of the fault codes. The vehicle had recently undergone a 50,000 mile routine service without any problems being flagged. The safety implications of this incident are clear: with no ability to match the speed of the flow of traffic, I could have been rear-ended or involved in a collision as I limped across the freeway to safety. I am fortunate that the vehicle had enough residual kinetic energy that I didn't end up stuck blocking a freeway lane in rush hour traffic. Searching online for similar issues, this appears to be a known manufacturing issue with the mild hybrid inline-6 engine in this model of vehicle. For instance, all of the top google hits for the term “gls 48v battery failure†yield relevant and similar reports from other drivers, including summaries from consumer lawyers like this one: https://lemberglaw. Com/mercedes-benz-gle-battery-electric-problems/ |
| Category | Engine, Fuel/propulsion System, Power Train |
| Date | May 19, 2022 |
| State | VA |
| Description | On numerous occasions, when either slowing down or in a slow turn, the engine dies and will not reengage until I have turned off the vehicle, exited, then reentered an started the vehicle. I have had passengers in the vehicle who will attest to this occurring, in fact, the last time it happened, I was almost broadsided when the vehicle stopped in the middle of a left-hand turn, crossing three lanes of oncoming traffic. The vehicle has been to the dealership at least three times and it's either a "software update" requirement or "we can't duplicate" the issue. When I called mb customer service, michael (initial intake) told me "I have seen this issue before." |
| Category | Electrical System, Engine, Fuel/propulsion System |
| Date | May 17, 2022 |
| State | AZ |
| Description | While driving, vehicle has abruptly stopped/engine turned off causing car to not accelerate and come to a stop. One instance was on a busy freeway, causing our family to pull off the interstate with nearly no curb, risking rear-end collision due to the abrupt stalling of the vehicle. In this instance, the 48 volt battery failure warning, engine overheat warning, engine light warning came on. When mcb dealership evaluated the vehicle, there were no stored associated error codes and mcb service returned the vehicle to me saying that the issue did not occur when they drove it. The same issue occurred again 5 months later, this time in a busy intersection, where the car would not accelerate and I was forced to pull of the road. The check engine light as well as other failure lights came on. The car was returned to mcb service and again, no error codes were stored and the dealership said they could not find the cause of the problem. This vehicle issue (reported to the nhtsa by several other 2020 gls owners) is a life-threatening dangerous vehicle problem . Both times, the engine abruptly failed and the car would not accelerate in the middle of heavily trafficked roads/freeways, which could easily result in a catastrophic accident. Both times, the vehicle did not store the associated error codes, despite the display illuminating several warning lights, including the check engine light. The unreliability of this expensive vehicle is particularly concerning to me as it is used to transport young children. Mercedes is taking no accountability for this vehicle failure and claims they have not heard of this issue prior, which is clearly inaccurate given that it has been reported to nhtsa by several other gls owners. This is an enormous safety liability, not only for the owners of this vehicle, but for innocent bystander drivers who could easily have a rear end collision with the car as it fails to accelerate and the engine abruptly stalls/stops. |
| Category | Electrical System |
| Date | Mar 08, 2022 |
| State | GA |
| Description | Mbux failure customer sold mb gls450 with all season mb floor matts, water on shoes drains on floor matts, car is driven and when braking water floods the underneath the front passenger seat and enters the mbux and shuts down all electronics. This was identified as an issue with mercedes benz and they are recommending a part that does not exist for a long term repair. Mercedes not taking responsibility for damage to mbux. Cost 8350 to repair |
| Category | Electrical System, Engine, Fuel/propulsion System |
| Date | Nov 02, 2021 |
| State | PA |
| Description | The vehicle warnign system displayed "48v malfunction." vehicke lost all acceleration in the middle of the highway. The vehicle was just returned3 days ago after undergoing a state inspection at the mb dealership. In looking at the issue on line this appears to be a known problem to mercedes. They are even facing a class action lawsuit for it in the same model year gle, which is based on many of the same systems. Someone is going to get killed when their vehicle stalls in the middl eof the highway. |
| Category | Electrical System, Unknown Or Other |
| Date | Oct 05, 2021 |
| State | MI |
| Description | Upon starting the car, the screen of the 2020 mercedes benz gls 450 remained blank. This includes the portion of the dashboard that reads speedometer, gas, temperature, rpm. The engine was running and truck could still be driven. The vehicle is available for inspection upon request. This is a major safety issue as the driver does not have visibility to the dashboard with all it's important information. The vehicle is currently at mercedes benz dealership undergoing diagnostics. The vehicle is being inspected by mercedes benz (manufacturer). See prior comment. There were no warning lamps or messages that appeared prior to the problem. Shortly after driving home (with the blank screen) the car was shut off and restarted and the display came back on but then the check engine light was displayed. |
| Category | Fuel/propulsion System, Power Train, Steering |
| Date | Aug 05, 2021 |
| State | CA |
| Description | We were driving the vehicle at about 30 mph on a road when suddenly the engine completely shut off. There was no more power steering and no warning that it turned off. We got the car slowed down and once we came to a stop the car put itself in park. After that we could restart it and keep driving with the car acting very different. This then happened again later on in the day going about 20 mph up to a stop light. It shut itself off and luckily we were able to come to a stop with the brakes without running into the intersection and no one hitting us from behind. Once again it put itself in park. We were able to restart the car and drive again with diminished power and really weird shifting from the transmission. The check engine light turned on both times and when we got it to the dealership the next morning all the check engine lights were off again. This is extremely dangerous to the driver and occupants. Our little son was in the back seat. We commute with this car in southern california and if this were to happen on the freeway it would be disastrous. Everyone is at risk with this car. It will just stop without any warning signs and you can have someone rear end you. And the power steering turns off also which if the car turns off in a corner on the freeway you will have no way of controlling the vehicle and will just go into the middle barrier or oncoming traffic. This could be even worse if driven on a mountain road and you loose all power of the vehicle. We will not be driving the car anymore since we have no idea when it will shut off again while driving. |
| Category | Electrical System |
| Date | Jun 17, 2021 |
| State | IL |
| Description | The vehicle issued a “48v battery malfunction†and the car warned me not to drive the vehicle under any circumstance. This was while driving at 55 mph on a country road. The dealer I bought the car from had 3 other cars brought in for the same issue. The dealer my car was towed to said they just had one with the same issue come in. Based on my reading, this is a serious issue and it appears that changing the battery does not correct the issue. I was transporting my entire family at the time. The thought of not being able to break when traveling at high speeds is terrifying. Seems to be a widespread issue on the newer cars. Mine is only a year old. |
| Category | Electrical System, Engine, Fuel/propulsion System |
| Date | Mar 14, 2021 |
| State | HI |
| Description | we purchased a new 2020 mercedes benz gls 450 in october 2019 from the oakland dealership and shipped the car to hawaii. The vehicle is now 117 months old and has about 4100 miles. Because our vehicle is lightly used we arranged for mercedes benz to supply and installed a 'battery minder' to keep the vehicles 48 volt system charged when we are away for an extended time. However we did not have the battery minder hooked up at this time because we are using the vehicle on a weekly basis. On march 7, 2021 we experienced a "48 volt battery malfunction' which left our car disabled on the side of an uphill major roadway. There was no warning just a sudden extreme loss of power, supplemental systems such as the ac deactivated, warning lights flashed and our vehicle coasted to the side of the road. I believe the brake system was also diminished by the loss of electrical boost. After a while we were able to restart the vehicle and began to 'limp home'. The vehicle was not able to accelerate and we experienced 'over heating' warnings ( in red ) and had to stop the vehicle to cool the engine. We arranged for mercedes benz roadside assistance to tow the vehicle to the kona mercedes benz service centre the next day. Yellow engine warning lights remained on when the vehicle was placed on the tow vehicle. We have used the kona service centre since it was opened, the team led by paulette gantala is very capable and they perform excellent work. After several days we learned that the cause of the malfunction was not found and we were told to 'monitor the situation'. I attached the service report which describes the extensive investigative work completed by the kona mercedes service centre. We are very concerned this malfunction is a safety related issue and needs to be escalated. Sudden unexpected loss of power creates extremely dangerous situations. |
| Category | Seats |
| Date | Nov 23, 2020 |
| State | CT |
| Description | Clip missing from right hand side passenger seat (2nd row), causing the seat to fold all the way forward multiple times on its own. This happened when the car was stationary. The dealership fixed the issue and added the missing clip. |
| Category | Electrical System |
| Date | Aug 06, 2020 |
| State | OH |
| Description | While driving the vehicle, a series of electrical system warnings were displayed in rapid succession. Shortly thereafter, the vehicle lost power, the engine shut off, and the vehicle began to glide. This incident occurred on a residential street while the vehicle was travelling at 25-30 mph. The warnings were specific to the 48v electrical system. The vehicle was operable after the incident and it was driven to the dealership. The repair invoice and the warning pictures are attached. The issue was traced to a grounding issue as most of the connections between the electrical system and the vehicle's chassis were inappropriately filled with paint (assumed from the vehicle assembly process). |
| Category | Fuel/propulsion System |
| Date | Jan 15, 2020 |
| State | TX |
| Description | Tl* the contact owns a 2020 mercedes-benz gls450. The contact stated she noticed a fuel odor coming from the vehicle when the windows were open. The contact sought medical attention due to breathing problems. The vehicle was taken to local dealer ed hicks imports located at 3102 s padre island dr, corpus christi, tx 78415 (361) 854-1955, where it was diagnosed the first time with a melting sticker on the cadillac and it needing to be removed. The vehicle was repaired but continue to experience the failure. The contact stated on 12/21/2019, while driving 7 mph, when she heard multiple loud abnormal noises (explosions). The vehicle was taken back to the same dealer, where it was diagnosed that the cadillac converter and turbo needed to be replaced. The vehicle had not been repaired as of yet. The manufacturer had not been informed of failure. The failure mileage was 1,000. |
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About the Author:
Brian Jones spent more than 20 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.
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