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9.6

really awful
Crashes / Fires:
0 / 0
Injuries / Deaths:
0 / 0
Average Mileage:
840 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2020 Mercedes-Benz GLS450 engine problems

engine problem

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2020 Mercedes-Benz GLS450 Owner Comments

problem #5

Sep 212022

GLS450

  • miles

A D V E R T I S E M E N T S

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 -€œshut down engine immediately-€. 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 -€œGLS 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/

- San Francisco, CA, USA

problem #4

Apr 272022

GLS450

  • miles
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."

- Woodbridge, VA, USA

problem #3

May 112022

GLS450

  • miles
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.

- Paradise Vly, AZ, USA

problem #2

Nov 022021

GLS450

  • miles
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.

- Newtown, PA, USA

problem #1

Mar 072021

GLS450

  • 4,200 miles
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.

- Kamuela, HI, USA

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