What is the 2017-2024 Mercedes-Benz GLC Active Brake Assist and 360-Degree Camera False Activations (Phantom Braking)?

GLC owners report the driver-assistance suite reacting to obstacles that are not there. The "checking surroundings" screen pops up several times a week with sections of the car outlined in red and nothing nearby, and — more seriously — Active Brake Assist has applied the brakes w… Repairs typically run $0-$1,500. Severity: high.

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

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… Repairs typically run $600-$2,500. Severity: high.

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

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. Repairs typically run $150-$2,500. Severity: medium.

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

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 o… Repairs typically run $800-$2,500. Severity: medium.

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

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 predominan… Repairs typically run $320-$2,200. Severity: medium.

What is the 2016-2022 Mercedes-Benz GLC Turbocharger Wastegate Actuator Diaphragm Rupture Causing Underboost and Limp Mode (M274/M264 2.0T)?

On the X253 GLC 300 the vacuum-operated turbo wastegate actuator uses a rubber diaphragm that hardens and tears after repeated heat cycling. Once it splits, the actuator can no longer hold vacuum, the wastegate hangs open, and the engine never builds commanded boost. The ECU logs… Repairs typically run $350-$900. Severity: medium.

What is the 2016-2024 Mercedes-Benz GLC LED Headlamp Moisture Ingress and Internal Condensation (Recall 22V261 plus Out-of-Recall Complaints)?

GLC headlamp assemblies collect water inside the lens. Mercedes recalled a narrow build window — 129 units of 2021 GLC 300, GLC 300 4MATIC, AMG GLC 43 and AMG GLC 63/63 S built May-June 2021 — because the sealing plugs in the headlamp connector housing were not properly installed… Repairs typically run $0-$2,200. Severity: medium.

What is the 2016-2022 Mercedes-Benz GLC Front Lower Spring Control Arm and Thrust Arm Bushing Wear Causing Clunk and Squeak?

X253 GLC owners report a heavy metallic clunk from the front end, most obvious over expansion joints and while turning, along with a squeak from the front suspension at low speed. The cause is the rubber bushings in the front lower spring control arm and the hydraulic (fluid-fill… Repairs typically run $600-$1,800. Severity: medium.

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

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. Repairs typically run $0-$500. Severity: low.

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

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 Elec… Repairs typically run $200-$600. Severity: low.

What is the 2016-2023 Mercedes-Benz GLC Power Tailgate Gas Support Strut Failure Causing the Liftgate to Drop or Slam Shut?

The GLC power tailgate uses a motorised spindle drive on one side and a gas-charged support strut on the other. When the gas charge leaks out of the passive strut, the tailgate no longer has enough force to stay up: owners describe the boot opening normally and then immediately c… Repairs typically run $120-$450. Severity: low.

Mercedes-Benz · Known Issues

2018 Mercedes-Benz GLC Problems: 14 Known Issues

2018 model year · 3,100+ owner reports · Updated September 2026

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According to Au7o's analysis of 3,100+ owner reports, the 2018 Mercedes-Benz GLC has 14 documented known issues, with 5 rated critical. The most serious are GLC 350e High-Voltage System Faults and Charging Failures (Plug-In Hybrid Only) ($900-$9,000 repair), SCR / AdBlue System Plausibility Failure Triggering a No-Restart Countdown (OM651 Diesel) ($400-$3,000 repair), Fixed Panoramic Roof Front and Side Trim Panels Debonding and Separating in Motion (Recall 17V715) ($0-$0 repair), Active Brake Assist and 360-Degree Camera False Activations (Phantom Braking) ($0-$1,500 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 with published estimates, repair costs range from $120 to $9,000. DIY maintenance guides at au7o.io.

Frequently Asked Questions

What are the most common Mercedes-Benz GLC problems?

According to Au7o's analysis of 3,100+ owner reports, the 2018 Mercedes-Benz GLC has 14 documented issues. The most frequently reported are: GLC 350e High-Voltage System Faults and Charging Failures (Plug-In Hybrid Only), SCR / AdBlue System Plausibility Failure Triggering a No-Restart Countdown (OM651 Diesel), Fixed Panoramic Roof Front and Side Trim Panels Debonding and Separating in Motion (Recall 17V715). Of these, 5 are rated critical and should be addressed promptly.

Is the Mercedes-Benz GLC reliable?

The 2018 Mercedes-Benz GLC has 14 known issues documented across 3,100+ owner reports. 5 issues are rated critical: GLC 350e High-Voltage System Faults and Charging Failures (Plug-In Hybrid Only) and SCR / AdBlue System Plausibility Failure Triggering a No-Restart Countdown (OM651 Diesel) and Fixed Panoramic Roof Front and Side Trim Panels Debonding and Separating in Motion (Recall 17V715) and Active Brake Assist and 360-Degree Camera False Activations (Phantom Braking) 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 $9,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, GLC 350e High-Voltage System Faults and Charging Failures (Plug-In Hybrid Only), typically costs $900-$9,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2016-2019 Mercedes-Benz GLC GLC 350e High-Voltage System Faults and Charging Failures (Plug-In Hybrid Only)?

The pre-facelift GLC 350e plug-in hybrid has a distinct set of high-voltage complaints that do not apply to the mild-hybrid or conventional GLC 300. Owners report a red battery malfunction telltale with the car refusing to start for several minutes, an amber engine light and the… Repairs typically run $900-$9,000. Severity: high.

All 14 Known Issues

Other Mercedes-Benz Models

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 is the 2016-2019 Mercedes-Benz GLC GLC 350e High-Voltage System Faults and Charging Failures (Plug-In Hybrid Only)?

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

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

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

2016-2022 Mercedes-Benz GLC: Turbocharger Wastegate Actuator Diaphragm Rupture Causing Underboost and Limp Mode (M274/M264 2.0T)#

2017-2018 Mercedes-Benz GLC: Fixed Panoramic Roof Front and Side Trim Panels Debonding and Separating in Motion (Recall 17V715)#

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

2016-2023 Mercedes-Benz GLC: Power Tailgate Gas Support Strut Failure Causing the Liftgate to Drop or Slam Shut#

2016-2019 Mercedes-Benz GLC: GLC 350e High-Voltage System Faults and Charging Failures (Plug-In Hybrid Only)#

2016-2022 Mercedes-Benz GLC: SCR / AdBlue System Plausibility Failure Triggering a No-Restart Countdown (OM651 Diesel)#

2017-2024 Mercedes-Benz GLC: Active Brake Assist and 360-Degree Camera False Activations (Phantom Braking)#

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

2016-2024 Mercedes-Benz GLC: LED Headlamp Moisture Ingress and Internal Condensation (Recall 22V261 plus Out-of-Recall Complaints)#

2016-2022 Mercedes-Benz GLC: Front Lower Spring Control Arm and Thrust Arm Bushing Wear Causing Clunk and Squeak#

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

What is the 2016-2022 Mercedes-Benz GLC SCR / AdBlue System Plausibility Failure Triggering a No-Restart Countdown (OM651 Diesel)?

What is the 2017-2018 Mercedes-Benz GLC Fixed Panoramic Roof Front and Side Trim Panels Debonding and Separating in Motion (Recall 17V715)?