A flashing check engine light on your 2018 Mercedes-Benz GLC signals an emergency condition—active misfires severe enough to damage the catalytic converter. Combined with P0302 indicating cylinder 2 misfire, you're facing a situation requiring immediate attention to prevent expensive secondary damage.
Why Flashing Check Engine Light Is Critical
Mercedes' ECU flashes the check engine light only when misfires are severe and continuous. Unburned fuel enters the exhaust system, potentially overheating and destroying the catalytic converter. The GLC's tight engine compartment means catalyst damage can affect surrounding components. Continuing to drive risks converting a repairable ignition or fuel issue into major repair expense.
P0302 Cylinder 2 Misfire Causes
The M274 engine in most GLC models can experience cylinder 2 misfire from ignition coil failure, spark plug degradation, fuel injector malfunction, or mechanical issues. A flashing light indicates the misfire is constant rather than intermittent, suggesting complete component failure rather than marginal performance.
Immediate Response
Stop driving when the check engine light flashes continuously. Pull over safely and either shut off the engine or have the vehicle towed. Brief operation in limp-home mode may be acceptable to reach safety, but extended driving causes catalyst damage that can cost thousands to repair.
Diagnostic Priority
Begin diagnosis with the ignition system—swapping the cylinder 2 coil with another cylinder quickly identifies coil failure. Check spark plug condition. If ignition tests good, evaluate fuel injector operation. Mechanical issues including compression loss are less common but possible. Repair the cause before any extended driving.