2016 Mercedes-Benz GLC Problems: 10 Known Issues

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.

On the 2016-2019 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.

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.

On the 2016-2019 Mercedes-Benz GLC M274 2.0L turbo I4, 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 M274 2.0-liter four-cylinder turbo engine in 2016-2019 cars (the M264 used from 2020 has an electronically controlled wastegate actuator) 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. On the M274 the wastegate actuator is generally not sold separately, so a confirmed actuator failure is usually repaired by replacing the turbocharger with its manifold.

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.

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.

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.

On the 2016-2018 Mercedes-Benz GLC, recall 18V683 covers certain 2016–2018 GLC300/GLC300 4MATIC, 2017–2018 AMG GLC43 4MATIC, and 2018 GLC350e and AMG GLC63 4MATIC vehicles. On this X253 population, a rear outboard belt's latch plate can retract between the C-pillar and rear side trim, preventing fastening. The U.S. campaign lists 4,702 vehicles; confirm inclusion by VIN.

On the 2016-2023 Mercedes-Benz GLC, on X253 GLCs with the automatically opening tailgate, a left and a right gas-charged support strut work together with the electric tailgate drive. 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 drive unit 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.

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-Benz LI42.10-P-065628 (January 2017) addresses front-axle squeal at low temperatures, typically on the first application and when reversing, with replacement brake pads and brake paste.