Last updated: 2026-10-10

RELIABILITY SCORE: 65/100 (GOOD)

2021 Mercedes-Benz GLB Reliability Report

Rated good but below average among 2021 SUVs, the 2021 Mercedes-Benz GLB has engine and cylinder head failures as its main concern.

Full Breakdown Compare Models

Recalls

Complaints

Complaint Rate

11.2per 10,000 sold

Est. Repair Cost

$908

Annual Fuel Cost

$2,850

Detailed Score Breakdown

Complaint Severity66/100

Component-weighted complaints normalized by sales volume

Repair Costs60/100

Independent repair cost ratings

Recall Impact57/100

Recall count weighted by severity

Issue Diversity83/100

Breadth of reported problem categories

The Verdict

Consider

Middle of the pack among GLB years, with engine and cylinder head failures and 10 recalls, fewer than 2020 but far more than 2022.

Top Issues to Watch

ELECTRICAL SYSTEM (5)
ENGINE (4)
POWER TRAIN (3)

Generation & Refresh (US)

Post-Redesign (Year 2)

2021 is year 2 of the First generation (X247; 2019).

Redesigned for the 2020 model year.
A refresh arrives in 2024.
1st generation GLB (US).

What this means for buyers

Year 2 is typically a safer pick than the first model year — early issues are more likely to be identified, but the platform is still new.

If you're comparing prices, check 2020 (redesign year) vs 2021+ pricing and recalls.

2020: First generation (X247; 2019) Launch

Generation start — new platform.

2021: This Model Year

2021 is year 2 of the First generation (X247; 2019).

2024: Mid-Cycle Refresh

Updated features and styling tweaks.

Should You Buy the 2021 Mercedes-Benz GLB?

Reliability stands at good, but this year rates below average against other 2021 SUVs. Among the GLB's scored years it sits in the middle of five. The 2020 rates worse. The 2022 rates better, with fewer complaints and no recalls. Federal crash testing gave 5 of 5 stars.

The serious complaints involve the engine. Owners report complete failure with little warning, in some cases at 35,000 miles, with shaking, power loss, and lockups on the interstate. Cylinder head failure shows up between 29,000 and 35,000 miles, and one engine seized again after the head was replaced. Electrical faults are harder to pin down: a random horn, a lost dashboard, and dealers finding no codes. Federal records list 10 recalls, including structure, air bags, and electronic stability control.

Ask for proof that every recall was completed and for engine service records. A 2022 is the neighbor to compare.

Compared to the 2022 Mercedes-Benz GLB, which scored 10 points higher. See also the 2020 Mercedes-Benz GLB for an earlier comparison.

Pros

+Acceptable reliability score
+Below-average complaint rate for SUV
+5-star NHTSA crash rating

Cons

−Above-average recall count
−UNKNOWN OR OTHER: Panoramic sunroof glass shatters while driving, with a sound like a gunshot and... (8 complaints)
−ELECTRICAL SYSTEM: Electrical faults cause sudden, hard-to-diagnose failures on the road (5 complaints)

Compare 2021 Mercedes-Benz GLB With

2021 Cadillac XT4

Reliability: 71/100

Good

2021 Buick Envision

Reliability: 74/100

Good

2021 Cadillac XT6

Reliability: 73/100

Good

2021 Infiniti QX60

Reliability: 81/100

Excellent

2021 Buick Encore GX

Reliability: 74/100

Good

Common Problem Categories

Safety

LOW RISK

10 manufacturer recalls issued

Other

HIGH RISK

UNKNOWN OR OTHER (8)
ELECTRICAL SYSTEM (5)

See detailed breakdown by component ↓

Recall Overview

recalls on record

The 2021 Mercedes-Benz GLB has 10 recalls on record, which is above average. A high count can flag multiple component concerns, though it also shows the manufacturer is actively addressing known issues.

NHTSA.gov →

Complaint Breakdown

11.2

per 10,000 sold

Segment avg: 16.7

LowAvgHigh

Moderate

Safety Incidents

Crashes

Fires

Injuries

Deaths

★★★★★

NHTSA 5/5 Stars

Data sourced from NHTSA complaint filings and manufacturer recall notices. Complaint narratives are owner-reported.

2021 Mercedes-Benz GLB Recall Details

10 recalls have been issued for the 2021 Mercedes-Benz GLB. All recall repairs are performed free of charge at authorized dealerships.

21V2310002021-04-01

STRUCTURE

Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021 GLB35 AMG, and 2020-2021 GLB250 vehicles. The side spoilers on the tailgate might not have been installed correctly, allowing them to detach.

Consequence

Detached spoilers can create a road hazard, increasing the risk of a crash or injury.

Remedy

MBUSA will notify owners, and dealers will inspect and, if necessary, replace the side spoilers, free of charge. Owner letters were mailed July 2, 2021. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2021050009.

21V2320002021-04-01

STRUCTURE

Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2020-2021 GLB250 vehicles. The wheel arch covers on the front fenders might not have been installed correctly, allow them to detach.

Consequence

Detached wheel arch covers can create a road hazard, increasing the risk of a crash or injury.

Remedy

MBUSA will notify owners, and dealers will check the installation of the front wheel arch covers and correct them as necessary, free of charge. Owner letters were mailed May 21, 2021. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2021040015.

22V6790002022-09-12

ELECTRONIC STABILITY CONTROL (ESC)

Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021 GLB250 vehicles. The Electronic Stability Program (ESP) unit may be damaged, which can result in disabled anti-lock brakes (ABS), disabled electronic stability control (ESC), and an electrical short circuit.

Consequence

Disabled anti-lock brakes and electronic stability control can increase the risk of a crash or injury. An electrical short circuit increases the risk of a fire.

Remedy

Dealers will replace the ESP unit, free of charge. Owner notification letters were mailed October 28, 2022. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2022090009.

VIN History Report

Buying a used 2021 Mercedes-Benz GLB? Check its history first

Electrical system problems lead owner complaints about the 2021 Mercedes-Benz GLB, and 10 recalls were issued for it. A VIN check shows whether this car's recall work was done, plus accident, title, and odometer history.

Accidents
Open Recalls
Title History
Odometer Rollback

2021 Mercedes-Benz GLB NHTSA Safety Ratings

Overall Safety Rating

Crash Test Results by Configuration (expand)

Gas Powertrain

Driver: 5/5Passenger: 4/5

Rollover risk: 15.9%

Safety Technologies

Dynamic Head Restraints (Not Available)Head Restraint (Driver, Front Passenger, Rear Seat, 3rd row)Advanced Belt Feature (Standard)Adjustable Upper Belt Anchorage (Driver, Front Passenger)Seat Belt Reminder System (Driver, Front Passenger)Frontal Air Bag (Driver, Front Passenger)Curtain (Driver, Front Passenger, Rear Seat, 3rd row)Torso/Pelvis (Driver, Front Passenger)Torso (Rear Seat)Knee (Driver)Additional Air Bags (PRE SAFE side Impulse)Meets Side Air Bag Out-of-Position Requirements (Yes)LATCH Locations (Rear Seat, 3rd row)Safety Power Windows (Anti-Pinch) (Standard)Safety Power Windows (Anti-Pinch) locations (Driver, Front Passenger, Rear Seat)

View full safety data on NHTSA.gov →

Mercedes-Benz GLBRepair Costs & Maintenance

Maintenance Rating

Based on NHTSA complaint patterns, recall severity, and publicly available cost benchmarks.

Est. Annual Maintenance

$908

Category-level averages derived from publicly available industry reports (AAA, CarMD). Model-level estimates produced by Auto Reliability Index.

MPG & Annual Running Costs

Gas

26 MPG

Running cost: $3,750/yr

Fuel + repair

23 city / 30–31 hwy MPG

Running cost includes EPA fuel-cost estimate and independent repair-cost data (repair cost estimated at model level). Excludes routine maintenance, depreciation, and insurance. Data as of 2021 EPA label cycle.

Gas trims

Trim	Drive	Trans.	City	Hwy	Comb	Fuel Cost
GLB250 2.0L 4-cyl	Front-Wheel Drive	Automatic (AM8)	23	31	26	$2,850
GLB250 4matic 2.0L 4-cyl	4-Wheel Drive	Automatic (AM8)	23	30	26	$2,850

Used Buying Checklist

Key things to inspect or verify before purchasing a 2021 Mercedes-Benz GLB.

Ask for records of any cylinder head work, engine replacement, or metal found in the oil.
Start the engine and listen for rough, diesel-like idle, shaking, or misfire warnings.
Inspect the panoramic sunroof glass for cracks or chips, and ask whether it has been replaced.
Drive slowly over bumps and through tight turns, and listen for front-end clunking or cracking.
Brake gently to a full stop several times and listen for clunks as the transmission downshifts.
Check for damp carpet or water stains near the windshield, and confirm the windshield-area drains are clear.
On a straight road, ease your grip on the wheel and watch for a pull to the left.
Run the VIN for open recalls and confirm the dealer has completed any listed repairs.

2021 Mercedes-Benz GLB Common Problems by Component

30 owner complaints grouped by vehicle system.

UNKNOWN OR OTHER (8)ELECTRICAL SYSTEM (5)ENGINE (4)POWER TRAIN (3)STEERING (2)SUSPENSION (2)VISIBILITY (1)VISIBILITY/WIPER (1)Other (3)

UNKNOWN OR OTHER

8 complaints

Panoramic sunroof glass shatters while driving, with a sound like a gunshot and glass falling into the cabin. Drivers report no impact beforehand, often at highway speed. Engine trouble also appears here. Cars sputter, jerk, and idle roughly. Dealers find cylinder head failure or metal particles in the oil, and some engines need replacement. A separate report says the transmission drops into neutral at speed after the car sits in the rain. One fuel door motor failed, and the car has no manual release.

8 complaints total

ELECTRICAL SYSTEM

5 complaints

Electrical faults cause sudden, hard-to-diagnose failures on the road. One car's horn sounds randomly while driving. Another shows a red transmission malfunction warning at highway speed and goes into limp mode. Dealers often cannot reproduce these faults or find stored codes. One car lost its whole dashboard while driving, and the dealer traced it to water entering near the windshield through a possibly clogged drain. Two of the five filings report no failure at all. Those owners describe long waits for parts needed to complete a recall repair.

5 complaints total

ENGINE

4 complaints

Complete failure is the main pattern, often with little warning and at mileages as low as 35,000. Owners describe heavy shaking, loss of power, loud noise, a check engine light, and refusal to accelerate. Some cars lock up on the interstate and leave the driver stranded. Shops report metal shavings in the oil, misfires, cylinder head failure, and bearing damage. The usual outcome is a full engine replacement, with high repair estimates and little help from the manufacturer. Losing power at highway speed creates a real crash risk.

4 complaints total

POWER TRAIN (3 complaints)

POWER TRAIN

3 complaints

Cylinder head failure leads to misfire warnings, rough idle, and sudden power loss. In one case the engine seized again after the dealer replaced the head, and the car sat at the shop for months. Another complaint describes a loud clunk from the left side on each downshift while coming to a stop. The dealer called it normal. A certified used car turned out to have leaking engine mounts, a missing mount screw, worn axles, and brake problems when it went in for routine service.

3 complaints total

STEERING (2 complaints)

STEERING

2 complaints

The front end develops loud clunking, thumping, and cracking noises from the axle area, mainly at low speeds. The noises can appear suddenly and get worse quickly. Some cars still pull left after the dealer replaces the front lower control arms and engine mounts and performs alignments. The driver then has to keep correcting the wheel to stay in the lane. Constant drift raises the risk of an unintended lane departure or loss of control.

2 complaints total

SUSPENSION (2 complaints)

SUSPENSION

2 complaints

A front ball joint can separate from the lower control arm with no warning. In the reported case the drive shaft came loose and the car stopped moving at about 15 mph. A transmission fault warning and loud grinding came first, and the car could not move in forward or reverse. A wheel failure like this at higher speed could cause a crash. A separate complaint describes skids at stops on snow and ice. That car came with summer tires, and the owner was never told.

2 complaints total

VISIBILITY (1 complaints)

VISIBILITY

1 complaint

2023-08-21

The contact owns a 2021 Mercedes-Benz GLB250. The contact stated that the vehicle was parked in the garage; however, after driving out of the garage, the contact became aware of a crack on the windshield from the rear-view mirror ten inches downward. The contact stated that the crack seemed to be on the inside over the sensors. The vehicle had not yet been diagnosed or repaired. The dealer nor manufacturer was notified of the failure. The failure mileage was 13,716.

VISIBILITY/WIPER (1 complaints)

VISIBILITY/WIPER

1 complaint

2025-12-10

Driving on north bound of Merritt Parkway between exit 17 and 18. Today 12/10/25 9:28 AM My panoramic sunroof exploded ! all catch on video, driver on the vehicle behind me , came to check on me; and told me the glass went over four feet up in the air and then hit his vehicle windshield, I call Mercedes Benz customer service support to report the incident and open a case, they told me to drive to the closest dealer from the incident (Mercedes Benz of Fairfield) when I arrived and show the vehicle to the technician, he was trying to tell me that was my fault and he never heard such a thing of a sunroof explosion… and was looking for a reason to blame me, I told him I got all on video due to I have a dash camera that records the our side and the inside of the vehicle.. the outside temperature was 30 degrees Fahrenheit, and the inside temperature in the vehicle was set to 69 degrees… My speed was 55 to 56 miles per hour. Light to moderate traffic, the explosion sound like a gunshot, that was my first impression, some one shoot at me… The dealer, told me that I should call my insurance or Mercedes Benz and the only think they can do, is to tell me how much will cost to repair the damage.. and that they will park my car on a different building so don’t get rain on it, until I decided what I want to do.

SEAT BELTS (1 complaints)

SEAT BELTS

1 complaint

2025-05-29

Seat belt failure.Driver side…mechanism… it feels unsafe…the retractor is not locking

TIRES (1 complaints)

TIRES

1 complaint

2024-08-16

The contact owns a 2021 Mercedes-Benz GLB250 equipped with Continental Tires, Tire Line: ProContact GX SSR, Tire Line: 235/55/R18, DOT Number: A33LWXX41220. The contact stated while driving 70 MPH, the vehicle began to vibrate with a flapping sound coming from the vehicle. Despite the failure, the contact was able to drive the vehicle to the residence. The contact then drove the vehicle to an independent mechanic where three humps were discovered on the front driver’s side tire that had formed due to thread separation on the inside of the tire. The mechanic referred the contact to a dealer who then referred the contact to the Continental tire manufacturer. The manufacturer informed the contact that the tire should be sent to the headquarters for an inspection. The tire was replaced. The failure mileage was approximately 30,600.

When Do 2021 Mercedes-Benz GLB Problems Start?

Based on owner complaint patterns, here's when common issues tend to appear.

29,000–35,000 milesCylinder head failure

Best & Worst Mercedes-Benz GLB Years

Best Mercedes-Benz GLB Years to Buy

Based on reliability index score

Top Pick

Good

Mercedes-Benz GLB Reliability Score Trend

Scores 0–100. Higher is better. Current year highlighted.

Mercedes-Benz GLB reliability scores by year
Year	Score	Rating
2020	59/100	Mixed
2021	65/100	Good
2022	75/100	Good
2023	74/100	Good
2024	72/100	Good

Mercedes-Benz GLB Reliability Compared to Other Years

Reliability scores compared across model years
Year	Score	vs Prior Year	Rating	Recalls	Complaints
2024	72/100	-2	Good	1	4
2023	74/100	-1	Good	0	12
2022	75/100	+10	Good	0	13
2021(selected)	65/100	+6	Good	10	30
2020	59/100	—	Mixed	19	56

Frequently Asked Questions

Is the 2021 Mercedes-Benz GLB reliable?

It rates good, but it falls below average against other 2021 SUVs. Within the GLB lineup it sits in the middle of five scored years. Owners filed 30 complaints, and the most serious involve engine failure. Federal crash testing gave it 5 of 5 stars.

What are the most common problems with the 2021 Mercedes-Benz GLB?

Electrical faults lead the complaints, followed by engine, power train, and steering problems. Owners describe random horn sounds, lost dashboards, engine failure, cylinder head failure, and clunking from the front end. Some cars still pull left after the dealer replaced control arms and engine mounts.

Does the 2021 Mercedes-Benz GLB have engine problems?

Yes, engine failure is a clear pattern in owner complaints. Cars have lost power, shaken heavily, or locked up on the interstate, sometimes at 35,000 miles. Shops report metal shavings in the oil, cylinder head failure, and bearing damage. The usual outcome is a full engine replacement.

How many recalls does the 2021 Mercedes-Benz GLB have?

Federal records list 10 recalls for this year. They cover structure, air bags, electronic stability control, communication electrical systems, suspension, exterior lighting, and back over prevention. Ask the seller for proof that each recall repair was completed before you buy.

Is the 2021 Mercedes-Benz GLB better than the 2020 or 2022?

It rates better than the 2020, which has 56 complaints and 19 recalls. The 2022 rates better than the 2021, with 13 complaints and no recalls. If you want fewer known problems, compare a 2022 against this year.

Don’t buy a 2021 Mercedes-Benz GLB without checking its VIN first — hidden accidents, title issues, and open recalls could cost you thousands.

Look Up a VIN →

How we score the 2021 Mercedes-Benz GLB

Of the four inputs behind this score, the 2021 Mercedes-Benz GLB does best on how many systems draw complaints (83/100) and worst on recall impact (57/100). Scores weight complaint severity at 35%, repair costs at 30%, recall impact at 20%, and the spread of complaints across systems at 15%, with complaint counts adjusted for US sales. Read the full methodology.

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