2021 Mercedes Benz Gls Class Recalls, Issues & Maintenance

The 2021 Mercedes Benz Gls Class has no open NHTSA recalls. Owners report 7 recurring issue clusters, led by “48V mild-hybrid battery system failure while driving.” Mercedes-Benz alternates two service events: Service A (oil, filter, inspection) at roughly 10,000 miles or 1 year, then Service B (Service A plus brake fluid, cabin filter, and deeper checks) at roughly 20,000 miles or 2 years — the ASSYST Plus counter in the cluster tells you which is due. Oil must carry the MB-Approval number your engine specifies (commonly 229.5, or 229.71 for newer 0W-20 engines); 'meets or exceeds' marketing language is not an approval. Electric EQB and EQS models keep the A/B rhythm for inspections, brake fluid, and cabin filters — just without oil.

No open recalls on file. NHTSA lists no unrepaired safety recalls for this year, make and model. A recall can be issued at any time, and a specific car can still have one open — check yours by VIN at nhtsa.gov/recalls.

Known issues for this vehicle

What drivers and federal regulators have officially reported about the 2021 Mercedes Benz Gls Class.

Reported to NHTSA

48V mild-hybrid battery system failure while driving

ELECTRICAL SYSTEM:12V/24V/48V BATTERY

15 NHTSA complaints · 2021-07 → 2026-07

Vehicle has just over 31k miles. ON multiple occasions, the vehicle randomly shuts off and displays a 48 volt battery error on the screen followed by a check engine light. This has happened in the middle of a busy intersection and at 75mph on the interstate
Owner report, NHTSA ODI #11624928
I was driving on [XXX] , the battery malfunction warning suddenly pop up, and I couldn't accelerate my car beyond 30 MPH, my whole family were on the car during that time. it's life threatening issue needs to be addressed
Owner report, NHTSA ODI #11634240
In July 2021, the vehicle became completely disabled due to failure of the 48 volt battery. In October 2021, the dealer replaced 48 volt battery failed again causing the vehicle to become completely disabled. In December 2023, our 3rd replacement 48 volt battery failed
Owner report, NHTSA ODI #11561635

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48V electrical system fire under passenger seat

ELECTRICAL SYSTEM, SEATS

3 NHTSA complaints · 2024-08 → 2025-05

I smelled smoke inside my car and saw fire flames coming from under my passenger seat. My initial reaction was to try to put the fire out with my hat without burning myself. Also, I had to try to navigate across multiple lanes of traffic without hitting anyone
Owner report, NHTSA ODI #11661377
Unknown, smoke started coming from under the passenger side seat, car is a complete loss. 2. Smoke damaged my lungs, there was a large amount of exploding glass, and it could have led to a structure…
Owner report, NHTSA ODI #11610699
Subsequent forensic diagnostics performed at an authorized secondary dealership (Mercedes-Benz of North Scottsdale) captured digital video evidence of active, high-voltage 48V electrical arcing across a completely loose, un-torqued main grounding network connection
Owner report, NHTSA ODI #11753406

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Spontaneous sunroof glass breakage

UNKNOWN OR OTHER

2 NHTSA complaints · 2022-04 → 2024-09

I was driving only 30mph through my suburban neighborhood bringing my kids to school in the morning when a loud shotgun sound hit my car causing me to be distracted and distraught. My entire sunroof had exploded on me for no reason
Owner report, NHTSA ODI #11616529
I was driving down the interstate and heard a loud ‘pop’. Very confused, my daughter and I saw a couple pieces of glass fall from the sunroof. Looked up to see the sky and hear the wind. Luckily, I had the shade closed
Owner report, NHTSA ODI #11462258

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Rear wheel cracking and tire pressure loss

WHEELS

1 NHTSA complaint · 2025-11 → 2025-11

Both rear wheels on this vehicle have developed cracks which leads to tire pressure loss. Apparently, this is a common issue with Mercedes' heavier vehicles like the GLS and S series sedans. To be clear, I did not hit anything. I did not do any unusual driving
Owner report, NHTSA ODI #11701188

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ADAS false alerts and unintended intervention

FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL, LANE DEPARTURE: BLIND SPOT DETECTION, ENGINE

4 NHTSA complaints · 2021-07 → 2023-01

while driving at various speeds, the Lane Departure safety feature independently activated as he attempted to avoid either a person or an object in the lane of traffic. As the contact attempted to steer around the pedestrian or object in the lane of traffic, the safety feature
Owner report, NHTSA ODI #11455544
The contact stated while driving 75 mph with the cruise control engaged, the vehicle decelerated to 45 mph than to 15 mph. On another occasion, while driving 80 mph, the vehicle independently decelerated to 45 mph. There was no warning light illuminated
Owner report, NHTSA ODI #11426426
The contact stated while driving at various speeds, the collision warning sensor was activated with an audio alarm and warning on the display screen. The contact stated that there were no objects in the roadway or close to the vehicle
Owner report, NHTSA ODI #11426863

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Mercedes Me account linked to prior owner after resale

UNKNOWN OR OTHER

2 NHTSA complaints · 2024-09 → 2024-09

Vehicle was purchased pre-owned. Mercedes Me is still associated with previous owner. Mercedes unable to remove association at dealership or on the phone. I can provide bill of sale and identification. Previous owner can remote start, track and control the vehicle I own.…
Owner report, NHTSA ODI #11613729
Vehicle was purchased pre-owned. Mercedes Me is still associated with previous owner. Mercedes unable to remove association at dealership or on the phone. I can provide bill of sale and identification. Previous owner can remote start, track and control the vehicle I own.…
Owner report, NHTSA ODI #11613731

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Windshield wiper chattering and skipping

VISIBILITY/WIPER

2 NHTSA complaints · 2022-10 → 2023-09

Continuous malfunctioning front windshield wipers. In light to medium rain/wet condition the wipers chatter/jump on the windshield, leaving residue on windshield and causing substantial distraction to driving and even discourages use of wipers (leaving visibility poor)
Owner report, NHTSA ODI #11491095
Wipers - I have had repeated issues with the windshield wipers on this vehicle. I have taken it to the dealership 3 times and I have not gotten a satisfactory solution to the issue. The wipers skip across the windshield making intermittent wipers distracting
Owner report, NHTSA ODI #11544975

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Source: NHTSA Office of Defects Investigation (ODI). Complaint data refreshed Sep 11, 2026. Investigation data refreshed Sep 11, 2026.

We display NHTSA's record with attribution; we don't editorialize on what these complaints mean for any specific vehicle.

Essential maintenance

Critical for safety and preventing major damage

Service A — Oil & Filter + Inspection

Every 10,000 mi

Every 10,000 miles or 12 months: oil and filter with MB-Approved oil, fluid top-offs, tire check, and inspection. AMG models driven hard: many owners service at 5,000-7,500 miles.

Estimated cost — typical U.S. ranges

Dealer

~$120–$160

Shop

~$85–$115

DIY

~$25–$55

Full synthetic costs more than conventional. 5-quart 0W-20 + filter is the typical bill.

Service B — Major Inspection

Every 20,000 mi

Every 20,000 miles or 2 years, alternating with Service A: everything in A plus brake-fluid replacement, cabin filter, and a deeper multi-point inspection of brakes, suspension, and driveline.

Estimated cost — typical U.S. ranges

Dealer

~$85

Shop

~$60

DIY

Free

Most shops do this free with any paid service. A flashlight and 10 minutes covers the basics yourself.

Tire Rotation

Every 10,000 mi

Rotate at every Service A where the tire sizes allow. Many AMG and 4MATIC+ models run staggered widths that can't rotate front-to-rear — check your spec before paying for a rotation.

Estimated cost — typical U.S. ranges

Dealer

~$85

Shop

~$60

DIY

Free

Often free at the shop where you bought the tires — worth asking before paying.

Brake Inspection

Every 10,000 mi

Checked at every A/B service via electronic pad-wear sensors. Replace sensors with pads. Heavy EQS models wear pads slowly (regen braking) but rotors can corrode from disuse — an inspection catches that.

Estimated cost — typical U.S. ranges

Dealer

~$85

Shop

~$60

DIY

Free

Most shops do this free as a courtesy with any service. Don't pay separately if you can avoid it.

Brake Fluid

Every 20,000 mi

Replaced every 2 years as part of Service B — Mercedes schedules it on time, not miles, because DOT 4 fluid absorbs moisture regardless of driving.

Estimated cost — typical U.S. ranges

Dealer

~$180–$200

Shop

~$125–$140

DIY

~$10–$25

DOT 3 or 4 — match the cap. Vacuum bleeders make this a one-person DIY.

Important maintenance

Keeps your vehicle running smoothly and efficiently

Automatic Transmission Fluid (7G / 9G-Tronic)

Every 70,000 mi

Mercedes specifies fluid and filter service around 70,000 miles on most 7G- and 9G-Tronic gearboxes — check your year's sheet. Use only the MB-spec fluid for your transmission code; independent specialists often service at 60,000 on hard-driven cars.

Estimated cost — typical U.S. ranges

Dealer

~$330–$500

Shop

~$235–$355

DIY

~$60–$180

Some sealed transmissions have no dipstick — fill is precise and best left to a shop. Many drivers can still DIY drain-and-fill.

Spark Plugs

Every 60,000 mi

Most modern MB gas engines: plugs around 60,000 miles — AMG engines often sooner. Check your engine's sheet; twin-turbo V8 plug jobs are labor-heavy, so pair with other scheduled work.

Estimated cost — typical U.S. ranges

Dealer

~$285–$390

Shop

~$200–$275

DIY

~$25–$100

Iridium plugs cost more but last 100k+ miles. V6/V8 access varies wildly — some are tough.

Engine Air Filter

Every 40,000 mi

Replace around every 40,000 miles (twin-filter setups on V6/V8 engines double the parts bill). Inspected at every Service B.

Estimated cost — typical U.S. ranges

Dealer

~$60–$95

Shop

~$45–$70

DIY

~$15–$40

5-minute job on most cars; the airbox lid usually has clips, no tools needed.

Recommended maintenance

Extends the life of your vehicle and improves comfort

Combination / Dust Filter

Every 20,000 mi

Replaced with every Service B. Models with the ENERGIZING air package use a higher-grade filter — priced accordingly.

Estimated cost — typical U.S. ranges

Dealer

~$60–$95

Shop

~$45–$70

DIY

~$15–$40

Usually behind the glovebox. Shops charge labor for a 10-minute job — easy DIY win.

Engine Coolant

On condition / lifetime

MB-spec coolant is long-life (typically ~10 years / 150,000 miles on the sheet). Refresh only with MB 325/326-spec coolant — the wrong chemistry attacks aluminum and head gaskets.

Estimated cost — typical U.S. ranges

Dealer

~$285–$330

Shop

~$200–$235

DIY

~$25–$60

Use the manufacturer-specified coolant — wrong color/chemistry can damage the cooling system.

12V & Auxiliary Battery

Every 25,000 mi

Test annually after year 3. Most modern Mercedes carry a second auxiliary battery; a weak one triggers cascading warning messages long before a no-start. EQ models also depend on the 12V system to boot.

Estimated cost — typical U.S. ranges

Dealer

~$225–$390

Shop

~$160–$280

DIY

~$130–$250

Most auto-parts stores test and install batteries free with purchase. Skip the dealer markup.

Fatal crash history & reported problems

Occupant deaths in fatal crashes (FARS)

No occupant deaths in FARS 2010–2024 crashes are on record for this year and model. That is the census answer for the window, and it says nothing more than that.

FARS counts every occupant death in a fatal crash, whatever the cause — it does not mean the vehicle was at fault or defective. Counts are not adjusted for how many of each vehicle are on the road. How to read this number

Owner-reported problem signals

Separate from the federal fatality data above: complaints owners filed with NHTSA about this year and model. These are reports of problems, unverified, and are counted here only as signals.

2

complaints mentioning a crash

2

complaints mentioning a fire

Reviewed known issues for this vehicle

Typical U.S. ranges. Actual quotes vary by shop, parts choice, and vehicle condition.

How we estimate: Dealer = OEM parts × 1.4 + labor × $165/hr. Shop = parts + labor × $115/hr. DIY = parts only.

This maintenance schedule for the 2021 Mercedes Benz Gls Class reflects Mercedes-Benz's published service intervals and the ASSYST Plus (Service A / Service B) system. Your actual service needs may vary based on driving conditions, climate, and vehicle usage. Always consult your owner's manual for model-specific recommendations.