Mercedes-Benz · Known Issues

2016-2026 Mercedes-Benz GLC Problems: 11 Issues Every Owner Should Know

2016-2026 model years · 4,200+ owner reports · Updated June 2026

According to Au7o's analysis of 4,200+ owner reports, the 2016-2026 Mercedes-Benz GLC has 11 documented known issues, with 5 rated critical. The most serious are Air Suspension Compressor Failure ($600-$2,000 repair), Steering Coupling Bolt Loosening / Loss of Steering Control (Recall) ($0-$0 repair), Fuel Pump Shutdown Causing Loss of Drive Power (Recall) ($0-$0 repair), 48V Mild-Hybrid (EQ Boost) Integrated Starter-Generator Failure ($1,000-$7,000 repair) and Diesel Timing Chain Tensioner Seal Oil Leak and Chain Stretch (OM651) ($600-$2,500 repair). The most commonly reported issue is 9G-Tronic Harsh Shifting with 2,000 owner reports. Across all issues, repair costs range from $150 to $7,000. DIY maintenance guides at au7o.io.

All 11 Known Issues

When Issues Typically Appear

9G-Tronic Harsh Shifting

5K-60K

MBUX Infotainment System Freeze

5K-40K

Panoramic Sunroof Creak and Rattle

10K-60K

Air Suspension Compressor Failure

30K-70K

025K50K75K100K mi

On the 2016-2019 Mercedes-Benz GLC OM651 2.1L diesel I4, eU-spec GLC 220d/250d diesels with the OM651 engine are prone to a leaking timing chain tensioner sealing ring, which causes oil loss at the chain tensioner and can lead to timing chain stretch and rattle. Mercedes recalled over 100,000 OM651 vehicles in Germany over sealing-ring manufacturing tolerances (CDI models built Feb-Nov 2014). Owners also report related diesel ailments: piezo injector faults, swirl-flap linkage failure, EGR/DPF clogging and oil-cooler gasket leaks. If the chain stretches far enough, valve-timing damage can result.

Common Symptoms

Timing chain rattle
Oil loss / drips near front of engine
Rough diesel running
Limp mode
Loss of power

How to Fix

Replace the timing chain tensioner and its seal (and the chain if stretched); for affected build dates have the German/EU recall sealing-ring remedy performed. Address associated diesel items (swirl flap actuator, injectors, EGR/DPF, oil-cooler gasket) as diagnosed.

Typical repair cost:$600 - $2,500

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Medium ConfidenceVerified0 reportsLast reported by owners Invalid DateReviewed Jun 2026

On the 2016-2019 Mercedes-Benz GLC M274 2.0L turbo I4, the integrated PCV / crankcase breather valve in the intake manifold (M274 2.0L turbo) commonly fails or its diaphragm tears, causing unmetered vacuum leaks. Oil mist can then migrate up the engine wiring harness via capillary action, contaminating connectors. Reported predominantly on 2016-2019 GLC 300 models. When ignored, lean running and loss of crankcase regulation risk further engine damage; in the worst cases the oil-soaked engine harness also requires replacement.

This issue also affects: Mercedes-Benz G-Class, Mercedes-Benz GLB, Mercedes-Benz SLC

Common Symptoms

Rough or unstable idle
Check engine light
Reduced fuel economy
Whistling/hissing vacuum leak noise
Oil in electrical connectors

How to Fix

Replace the PCV/crankcase ventilation valve (integrated into intake manifold/oil separator). If oil has wicked into the engine harness connectors, the affected harness section must also be replaced. Inspect connectors for oil intrusion at the same time.

Typical repair cost:$320 - $2,200

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High ConfidenceVerified0 reportsLast reported by owners Invalid DateReviewed Jun 2026

On the 2016-2023 Mercedes-Benz GLC, on the M274/M264 2.0L turbo engines used in the GLC, the intake camshaft adjuster relies on an internal locking pin that wears over time. Without oil pressure at cold start, the adjuster fails to lock in its default position, producing a distinct metallic rattle for 2-4 seconds on a cold start. Oil leaking around the camshaft adjuster solenoid can also seep into the wiring harness and trigger timing faults. Left unrepaired it risks valve-timing errors and further engine wear.

This issue also affects: Mercedes-Benz B-Class, Mercedes-Benz CLA, Mercedes-Benz G-Class

Common Symptoms

Loud metallic rattle for 2-4 seconds on cold start
Check engine light
Rough running until warm

How to Fix

Replace the camshaft adjuster(s) and/or the camshaft magnet/solenoid actuators; use of fresh, correct-spec oil and addressing any oil-pressure deficiency is part of the fix. Verify no oil contamination has reached the solenoid connectors.

Typical repair cost:$800 - $2,500

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High ConfidenceVerified0 reportsLast reported by owners Invalid DateReviewed Jun 2026

On the 2020-2023 Mercedes-Benz GLC M264 2.0L turbo I4 (EQ Boost mild hybrid), gLC 300 models with the M264 engine use a 48-volt mild-hybrid system with an Integrated Starter-Generator (ISG) mounted between the engine and transmission, fed by a small lithium-ion battery. The ISG, its 48V battery, or a loose/overheating 48V ground connection can fail, triggering a '48V On-Board Electrical System Malfunction' warning. Failures often cause a no-start condition that cannot be jump-started, stalling while driving, or in severe cases overheated connections posing a fire risk. Because the ISG sits between engine and gearbox, repair is labor-intensive and expensive.

Common Symptoms

48V electrical system malfunction warning
No-start that cannot be jump-started
Engine stall while driving
Loss of auto start-stop function
Burning smell from overheated connection

How to Fix

Diagnose the 48V circuit; remedies range from re-securing/replacing the 48V ground connection or the 48V lithium battery to replacing the ISG itself (which typically requires transmission removal). Address any related Mercedes 48V recall/service campaign for the affected connection.

Typical repair cost:$1,000 - $7,000

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High ConfidenceVerified0 reportsLast reported by owners Invalid DateReviewed Jun 2026

Community Reported

700 owners

On the 2020-2025 Mercedes-Benz GLC, the MBUX infotainment system freezes, reboots, or displays a black screen. Bluetooth connections drop, Apple CarPlay/Android Auto disconnects randomly, and the voice assistant becomes unresponsive.

This issue also affects: Mercedes-Benz EQB, Mercedes-Benz GLB, Mercedes-Benz GLE

Common Symptoms

Touchscreen unresponsive to input
System reboots with Mercedes logo

How to Fix

Perform a system reboot by holding the volume and track-forward buttons for 10 seconds. Visit a dealer for the latest MBUX software update. If freezes persist, the head unit may need replacement.

What you need to fix it

The exact parts — OEM, plus what owners actually use. Skip the internet hunt.

From owners — upgrades & tips (700+ fixed this)

TipDisable wireless CarPlay and use a USB cable instead. Wireless connections cause more MBUX stability issues than wired.

Part links may earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$0 - $2,000

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Medium Confidence700 reportsLast reported by owners Dec 2025Reviewed Mar 2026

Community Reported

400 owners

On the 2020-2025 Mercedes-Benz GLC, gLC models equipped with optional AIRMATIC air suspension experience premature compressor failure. The compressor overheats from compensating for minor air spring leaks and eventually burns out, leaving the vehicle in a lowered position.

This issue also affects: Mercedes-Benz AMG GT 4-Door, Mercedes-Benz GL-Class, Mercedes-Benz GLE

Common Symptoms

Vehicle sitting low after overnight parking
Suspension warning light on dashboard

How to Fix

Replace the air compressor and relay. Check all four air springs for slow leaks before installing a new compressor. The Arnott P-3508 is a reliable aftermarket alternative.

What you need to fix it

The exact parts — OEM, plus what owners actually use. Skip the internet hunt.

From owners — upgrades & tips (400+ fixed this)

TipListen for the compressor running after you park. If you hear it cycling repeatedly, you have an air leak that will kill the compressor. Get it inspected promptly.

Part links may earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$600 - $2,000

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Medium Confidence400 reportsLast reported by owners Nov 2025Reviewed Mar 2026

On the 2023-2026 Mercedes-Benz GLC, on certain 2023-2026 GLC 300 and GLC 300 4MATIC vehicles, the steering coupling bolt may have been improperly tightened at the factory, allowing the steering coupling to loosen from the steering rack. This can lead to a loss of steering control and an increased risk of a crash. NHTSA recall 25V533 covers roughly 3,749 affected vehicles.

Common Symptoms

Loose or vague steering feel
Clunk from steering column
Loss of steering control

How to Fix

Under recall 25V533, dealers inspect and tighten (or rework) the steering coupling bolt connection to specification, free of charge. Owners should verify their VIN and have the inspection performed promptly.

Typical repair cost:$0 - $0

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On the 2021-2023 Mercedes-Benz GLC M264 2.0L turbo I4, the fuel pump impeller on certain 2021-2023 GLC vehicles may not meet material specifications, allowing the fuel pump to shut down and causing a sudden loss of drive power while driving. This was the subject of a large NHTSA recall covering 143,551 Mercedes vehicles across multiple model lines including the GLC.

Common Symptoms

Sudden loss of drive power while driving
Engine stall
No-start / hard start

How to Fix

Under the recall, dealers replace the fuel pump free of charge. Owners should check their VIN against NHTSA campaigns 23V445 (and expansion 23V880) and have the pump replaced.

Typical repair cost:$0 - $0

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High ConfidenceVerified0 reportsLast reported by owners Invalid DateReviewed Jun 2026

Community Reported

2,000 owners

On the 2016-2022 Mercedes-Benz GLC, the 9G-Tronic (725.0) nine-speed automatic transmission exhibits harsh downshifts and jerky low-speed behavior, particularly the 1-2 and 2-1 shifts. The transmission software struggles with the many gear ratios at parking lot speeds.

This issue also affects: Mercedes-Benz C-Class, Mercedes-Benz GLS

Common Symptoms

Harsh 1-2 upshift at low speeds
Jerky behavior in parking lots

How to Fix

Update the transmission control unit (TCU) software to the latest calibration at a Mercedes dealer. Perform a transmission adaptation reset. If software updates do not help, the valve body may need replacement.

What you need to fix it

The exact parts — OEM, plus what owners actually use. Skip the internet hunt.

From owners — upgrades & tips (2,000+ fixed this)

TipAsk the dealer specifically for the latest TCU calibration update. Mercedes has released multiple revisions to improve low-speed shift quality on the 9G-Tronic.

Part links may earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$150 - $2,500

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High Confidence2,000 reportsLast reported by owners Nov 2025Reviewed Mar 2026

Community Reported

1,100 owners

On the 2016-2023 Mercedes-Benz GLC, the panoramic sunroof develops creaking and rattling noises over bumps and temperature changes. The glass panel expands and contracts differently than the metal frame, creating friction-induced squeaks especially in cold weather.

This issue also affects: Mercedes-Benz GLB

Common Symptoms

Creaking noise from roof over bumps
Rattling in cold weather

How to Fix

Apply silicone-based lubricant to the sunroof seal and guide rails. The dealer can adjust the glass panel alignment and apply felt tape to contact points under warranty. Clean and lubricate the rails twice yearly.

What you need to fix it

The exact parts — OEM, plus what owners actually use. Skip the internet hunt.

From owners — upgrades & tips (1,100+ fixed this)

TipApply Gummi Pflege (rubber care) to the sunroof seals every 6 months. This German rubber conditioner prevents the seals from drying out and squeaking against the glass.

Part links may earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$0 - $500

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Medium Confidence1,100 reportsLast reported by owners Dec 2025Reviewed Mar 2026

On the 2016-2019 Mercedes-Benz GLC, early X253 GLCs (2016-2019) are widely reported to squeal from the brakes, especially when backing up or in cold/damp weather, partly due to glazed pads and moisture trapped in drilled rotor holes. Separately, the rear brakes wear out noticeably before the fronts because the Electronic Parking Brake actuates the rear calipers each time the car is shut off. Mercedes updated the brake pads from the 2020 model year to address the squeal.

Common Symptoms

Brake squeal, especially in reverse or cold weather
Rear pads worn out before fronts
Squeal when backing up

How to Fix

Fit updated/quality (often aftermarket) brake pads to cure the squeal; clean/resurface or replace rotors as needed. Replace worn rear pads early and put the Electronic Parking Brake into service mode before any rear brake work to avoid damaging the actuators.

Typical repair cost:$200 - $600

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Frequently Asked Questions

What are the most common Mercedes-Benz GLC problems?

According to Au7o's analysis of 4,200+ owner reports, the 2016-2026 Mercedes-Benz GLC has 11 documented issues. The most frequently reported are: Air Suspension Compressor Failure, Steering Coupling Bolt Loosening / Loss of Steering Control (Recall), Fuel Pump Shutdown Causing Loss of Drive Power (Recall). Of these, 5 are rated critical and should be addressed promptly.

Is the Mercedes-Benz GLC reliable?

The 2016-2026 Mercedes-Benz GLC has 11 known issues documented across 4,200+ owner reports. 5 issues are rated critical: Air Suspension Compressor Failure and Steering Coupling Bolt Loosening / Loss of Steering Control (Recall) and Fuel Pump Shutdown Causing Loss of Drive Power (Recall) and 48V Mild-Hybrid (EQ Boost) Integrated Starter-Generator Failure and Diesel Timing Chain Tensioner Seal Oil Leak and Chain Stretch (OM651). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Mercedes-Benz GLC problems?

Repair costs for known Mercedes-Benz GLC issues range from $0 to $7,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Air Suspension Compressor Failure, typically costs $600-$2,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What year Mercedes-Benz GLC is the most reliable?

Reliability varies across model years of the Mercedes-Benz GLC. Based on documented issues, problems are most commonly reported in earlier model years. Au7o recommends checking the specific known issues for your target year before purchasing, and having a pre-purchase inspection performed by a qualified mechanic. Our known issues database covers the 2016-2026 Mercedes-Benz GLC with 11 documented issues documented across 4,200+ owner reports.

What is the 2020-2025 Mercedes-Benz GLC Air Suspension Compressor Failure?

GLC models equipped with optional AIRMATIC air suspension experience premature compressor failure. The compressor overheats from compensating for minor air spring leaks and eventually burns out, leaving the vehicle in a lowered position. Repairs typically run $600-$2,000. Severity: high.

All 11 Known Issues

When Issues Typically Appear

2016-2019 Mercedes-Benz GLC: Diesel Timing Chain Tensioner Seal Oil Leak and Chain Stretch (OM651)#

Common Symptoms

How to Fix

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2016-2019 Mercedes-Benz GLC: Crankcase Vent (PCV) Valve Failure with Engine Harness Oil Contamination#

Common Symptoms

How to Fix

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2016-2023 Mercedes-Benz GLC: Cold-Start Camshaft Adjuster (Magnet/Solenoid) Rattle#

Common Symptoms

How to Fix

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2020-2023 Mercedes-Benz GLC: 48V Mild-Hybrid (EQ Boost) Integrated Starter-Generator Failure#

Common Symptoms

How to Fix

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2020-2025 Mercedes-Benz GLC: MBUX Infotainment System Freeze#

Common Symptoms

How to Fix

What you need to fix it

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2020-2025 Mercedes-Benz GLC: Air Suspension Compressor Failure#

Common Symptoms

How to Fix

What you need to fix it

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2023-2026 Mercedes-Benz GLC: Steering Coupling Bolt Loosening / Loss of Steering Control (Recall)#

Common Symptoms

How to Fix

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2021-2023 Mercedes-Benz GLC: Fuel Pump Shutdown Causing Loss of Drive Power (Recall)#

Common Symptoms

How to Fix

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2016-2022 Mercedes-Benz GLC: 9G-Tronic Harsh Shifting#

Common Symptoms

How to Fix

What you need to fix it

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2016-2023 Mercedes-Benz GLC: Panoramic Sunroof Creak and Rattle#

Common Symptoms

How to Fix

What you need to fix it

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2016-2019 Mercedes-Benz GLC: Rear Brake Squeal and Premature Rear Pad Wear#

Common Symptoms

How to Fix

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Frequently Asked Questions

What are the most common Mercedes-Benz GLC problems?

Is the Mercedes-Benz GLC reliable?

How much does it cost to fix common Mercedes-Benz GLC problems?

What year Mercedes-Benz GLC is the most reliable?

What is the 2020-2025 Mercedes-Benz GLC Air Suspension Compressor Failure?

What is the 2023-2026 Mercedes-Benz GLC Steering Coupling Bolt Loosening / Loss of Steering Control (Recall)?

What is the 2021-2023 Mercedes-Benz GLC Fuel Pump Shutdown Causing Loss of Drive Power (Recall)?

What is the 2020-2023 Mercedes-Benz GLC 48V Mild-Hybrid (EQ Boost) Integrated Starter-Generator Failure?

What is the 2016-2019 Mercedes-Benz GLC Diesel Timing Chain Tensioner Seal Oil Leak and Chain Stretch (OM651)?

What is the 2016-2022 Mercedes-Benz GLC 9G-Tronic Harsh Shifting?

What is the 2016-2019 Mercedes-Benz GLC Crankcase Vent (PCV) Valve Failure with Engine Harness Oil Contamination?

What is the 2016-2023 Mercedes-Benz GLC Cold-Start Camshaft Adjuster (Magnet/Solenoid) Rattle?

What is the 2016-2023 Mercedes-Benz GLC Panoramic Sunroof Creak and Rattle?

What is the 2020-2025 Mercedes-Benz GLC MBUX Infotainment System Freeze?

What is the 2016-2019 Mercedes-Benz GLC Rear Brake Squeal and Premature Rear Pad Wear?