According to Au7o's analysis of 3,100+ owner reports, the 2019 Mercedes-Benz GLC has 13 documented known issues, with 4 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), 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.
What are the most common Mercedes-Benz GLC problems?
According to Au7o's analysis of 3,100+ owner reports, the 2019 Mercedes-Benz GLC has 13 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), Active Brake Assist and 360-Degree Camera False Activations (Phantom Braking). Of these, 4 are rated critical and should be addressed promptly.
Is the Mercedes-Benz GLC reliable?
The 2019 Mercedes-Benz GLC has 13 known issues documented across 3,100+ owner reports. 4 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 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.
What is the 2016-2022 Mercedes-Benz GLC SCR / AdBlue System Plausibility Failure Triggering a No-Restart Countdown (OM651 Diesel)?
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.
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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.
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.
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.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
Genuine Mercedes-Benz M274/M264 intake and exhaust camshaft sprocket-adjuster kit 2600502100KT
OEMMercedes-Benz 2600502100KT
Confirmed internal intake/exhaust camshaft adjuster failure branch Fitment/availability: The inspected direct U.S. Confirm VIN,
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.
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.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
Confirmed failed M274 intake-line/partial-load ventilation assembly branch for applicable 2015-2018 non-hybrid GLC300 Fitment/availability: The inspected direct U.S.
On the 2016-2022 Mercedes-Benz GLC, 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 an underboost fault and drops the car into reduced-power limp mode, often intermittently at first (a flat spot on hard acceleration, sometimes a rattle or hiss from the turbo area) before becoming a hard fault. This is specific to the 2.0-liter four-cylinder turbo engines (M274 in earlier cars, M264 in the 48V-equipped later ones) and is NOT the same failure as the camshaft adjuster rattle or the PCV/crankcase-vent problem, both of which sit on the same engine but have different symptoms and different repairs. Owners are frequently quoted for a whole turbocharger when only the actuator has failed.
Common Symptoms
Check engine light with reduced power
Limp mode / EPC warning under acceleration
Flat spot or loss of boost on hard throttle
Rattle or hiss from the turbocharger area
Fluctuating boost pressure
How to Fix
Apply a hand vacuum test to the actuator and confirm it cannot hold vacuum or sweep the rod, then inspect boost/vacuum lines and linkage. Replace and calibrate only the confirmed actuator branch; do not replace the turbo for a hose or control fault.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
2740904380 aftermarket turbo wastegate actuator
$46
Direct listing covers 2016 GLC300 and 2018-2020 GLC350e applications using the specified M274-family interchange. It does not establish fitment for every 2016-2022 M274/M264 GLC; match the OE number and VIN before purchase.
On the 2016-2019 Mercedes-Benz GLC, 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 air conditioning blowing hot — in at least one documented case the dealer traced the high-voltage battery fault to the ELECTRIC A/C COMPRESSOR, which sits on the high-voltage bus and can pull the whole HV system into a fault state. Separately, owners report the car will not accept a charge at all: the charging station shows no response from the vehicle and the session never starts. Usable electric range also falls faster than expected on some cars, with owners reporting a drop from roughly 34 km to 26 km. Because these are HV-side faults they fall under hybrid component coverage rather than the basic warranty, and the diagnosis path is different from any 12V or 48V complaint.
Common Symptoms
Red battery malfunction warning on the cluster
Vehicle will not start for several minutes
Air conditioning blows warm with an HV fault stored
Charging station does not begin a session
Electric-only range falls noticeably
How to Fix
Test with a known-good EVSE/cable and read the high-voltage bus to separate charge-port pilot, onboard charger, electric compressor and battery faults. Establish hybrid-component coverage before authorizing parts; retail HV components are not appropriate without isolation and safety procedures.
On the 2016-2022 Mercedes-Benz GLC OM651 2.1L diesel I4, european-market GLC 220d and 250d models with the OM651 diesel run an SCR aftertreatment system that will refuse to allow further engine starts once the control unit loses confidence in NOx conversion. Owners and technicians report the dash showing "Engine start not possible in xxx km" while the SCR/AdBlue system stores NO diagnostic trouble codes at all, which makes the fault very hard to chase — a documented case on a C253 GLC 220d with engine OM651.921 showed exactly this pattern. The underlying cause is rarely one failed part: the reductant metering unit, the AdBlue supply pump and lines, the NOx sensors and SCR catalyst efficiency all feed the same plausibility model, so drift in any of them collapses the calculated conversion rate. This is engine-code specific to the OM651 diesel, does not apply to the petrol GLC 300 or the 350e, and is a separate fault path from the OM651 timing chain tensioner oil leak.
Common Symptoms
"Engine start not possible in xxx km" countdown on the dash
AdBlue warning with no stored fault codes
Reduced power / limp mode
AdBlue consumption higher than normal
White crystalline deposits around AdBlue lines or injector
How to Fix
Use XENTRY-equivalent live data to establish SCR efficiency and upstream/downstream NOx-sensor behavior, verify DEF quality and inspect dosing lines for crystallization. Check emissions campaigns before ordering; a tank, pump or NOx sensor is not approved without the diagnosed branch.
On the 2017-2024 Mercedes-Benz GLC, 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 with no vehicle or object ahead. Owners on the Mercedes forums describe the system cutting the accelerator because it believes an obstacle is present, and multiple owners across the GLC and its C-Class platform siblings report the same event, encouraging one another to file NHTSA complaints. Mercedes has attributed comparable behaviour on other models to a software error in the radar sensor control unit, and the general failure mode is the radar or camera misreading a roadside object as a collision threat. An unexpected full-force brake application in traffic is a rear-end collision risk.
Common Symptoms
Sudden hard braking with no vehicle or object ahead
"Checking surroundings" alert with red outlines and nothing nearby
Accelerator unresponsive during a false activation
Collision warning chime on an empty road
"Active Brake Assist functions limited" message
How to Fix
Read radar/camera event memory, install the current control-unit software and check sensor alignment/calibration, especially after glass or front-end work. No sensor or camera is approved until a specific failed component is established.
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.
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
Only diagnosis- and fitment-reviewed repair parts are linked here.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
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.
Medium Confidence1,100 owner reportsLast reported by owners Dec 2025Reviewed Mar 2026
On the 2016-2023 Mercedes-Benz GLC, 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 closing again faster than normal, or drifting down onto the person loading the car. Because the electric drive is still working, the symptom is easily misread as a liftgate motor or module fault and owners are quoted for the expensive spindle drive when the failed part is the inexpensive gas strut. A tailgate that comes down under its own weight is a genuine head and hand injury risk.
Common Symptoms
Tailgate opens then immediately closes
Tailgate will not stay up when opened by hand
Tailgate drifts down while loading
Power liftgate reverses part way through its cycle
How to Fix
Manually test whether the open liftgate holds and verify 12V condition before blaming the support. For a weak pneumatic support, replace both supports together and keep the liftgate mechanically supported during service; power-spindle, wiring and software faults are different branches.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
Genuine Mercedes-Benz 253-980-03-00 pneumatic lift support
$59
2016-2022 X253 GLC300, 2018-2020 GLC350e, 2017-2022 GLC43 AMG and 2018-2021 GLC63 AMG applications listed by the OEM catalog. Not the C253 coupe or 2023 X254 branch; quantity two is required for the stated pair repair.
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.
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.
Owner tips & cautions
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.
High Confidence2,000 owner reportsLast reported by owners Nov 2025Reviewed Mar 2026
On the 2016-2024 Mercedes-Benz GLC, 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, letting water reach the electrical connection and causing headlight failure. Beyond that recall population, owners across the X253 and X254 generations report heavy condensation inside LED headlights from compromised gaskets or blocked vent tubes, including new X254 cars fogging on one side, being replaced, and then fogging on the other. Dealers have handled non-recall cases by inserting silica gel desiccant bags under warranty, which owners describe as a temporary measure rather than a repair.
Common Symptoms
Fog or visible water droplets inside the headlamp lens
One or both LED headlights inoperative
Condensation that clears slowly or not at all
Repeat condensation after a headlamp replacement
How to Fix
If the VIN falls in recall 22V261 (MBUSA campaign 2022050005), the dealer inspects and replaces the headlamp sealing plugs free of charge. Outside that population the correct diagnosis is to check the housing vent tubes for blockage and the rear cap and gasket seals for cracks or an improperly seated LED cover — silica bags treat the symptom only. Persistent water intrusion with an intact seal is grounds for a headlamp assembly replacement under the new-vehicle warranty; out of warranty a full LED unit is expensive, so pursue the claim while coverage lasts.
On the 2016-2022 Mercedes-Benz GLC, 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-filled) thrust arm bushing, which soften and split well before the mileage owners expect — one owner documented replacement of the front suspension bushes at 38,000 miles. The fluid-filled thrust-arm bushing is the more frequent failure. Mercedes does not sell the spring-arm bushings separately, so the complete control arm assembly has to be replaced. This is a suspension-link failure and should not be confused with AIRMATIC air-suspension compressor faults, which produce a ride-height complaint rather than a clunk.
Common Symptoms
Metallic clunk from the front suspension over bumps
Clunk more noticeable while turning
Squeak from the front end at low speed
Vague or wandering steering feel
Uneven front tire wear
How to Fix
Inspect the loaded suspension and identify the exact lower spring-arm or thrust-arm position with torn or leaking bushings. Replace complete confirmed arms in axle pairs as appropriate and perform a four-wheel alignment.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
Lemfoerder W0133-2138557 front-left lower-forward control arm
$212
This link covers only that confirmed corner/arm, not the opposite side, rearward thrust arm, AMG or air-suspension branches.
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.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
Worn or damaged 320 x 24 mm X253 rear pads-and-rotors replacement branch Fitment/availability: The inspected direct U.S. page identifies KIT-X253BR320 for GLC300 and GLC350e, showed it in stock with purchase controls, and the kit contain…
European-market GLC 220d and 250d models with the OM651 diesel run an SCR aftertreatment system that will refuse to allow further engine starts once the control unit loses confidence in NOx conversion. Owners and technicians report the dash showing "Engine start not possible in x… Repairs typically run $400-$3,000. Severity: high.
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.
