The 2024 Mercedes-Benz GLE luxury SUV offers the M256 3.0-liter turbocharged inline-6 engine in GLE 450 and GLE 450e plug-in hybrid variants. A P0305 diagnostic trouble code indicates the powertrain control module has detected a misfire condition specifically at cylinder 5 of this six-cylinder engine.
P0305 Code Analysis for GLE Inline-6
The P0305 code signifies "Cylinder 5 Misfire Detected," and on the M256 inline-6 engine, cylinder 5 is a legitimate cylinder position. Located fifth from the front of the engine, cylinder 5 fires second in the 1-5-3-6-2-4 firing order. Misfires at this position affect engine smoothness and performance.
Common Cylinder 5 Misfire Causes
The M256 engine's sophisticated design doesn't eliminate common misfire causes. Cylinder 5 misfires typically stem from ignition coil degradation, spark plug wear at or beyond the 60,000-mile service interval, fuel injector fouling or failure, intake valve carbon deposits from direct injection, or mechanical issues affecting compression.
Mild-Hybrid System Integration
The GLE's 48-volt mild-hybrid system with integrated starter-generator adds complexity to the powertrain. Electrical system irregularities can affect ignition timing precision, though they rarely cause isolated single-cylinder misfires. The electric auxiliary compressor provides immediate boost response.
Professional Diagnostic Requirements
Accurate P0305 diagnosis on your GLE requires Mercedes-Benz XENTRY diagnostic equipment for detailed misfire counter analysis, freeze frame data interpretation, and cylinder-specific testing capabilities. Component testing should focus on cylinder 5 ignition, fuel delivery, and mechanical integrity.