The 2022 Mercedes-Benz GLE W167 luxury SUV features the M256 3.0-liter turbocharged inline-6 engine with EQ Boost mild-hybrid technology in GLE 450 variants. A P0305 diagnostic trouble code indicates that cylinder 5 of this six-cylinder engine is experiencing misfire events detected by the crankshaft position sensor.
Understanding P0305 on M256 Engine
P0305 translates to "Cylinder 5 Misfire Detected" in OBD-II terminology. The M256 inline-6 configuration places cylinder 5 as the fifth from the front in a row of six cylinders. With a firing order of 1-5-3-6-2-4, cylinder 5 is second to fire and contributes significantly to engine smoothness.
Root Causes of Cylinder 5 Misfire
Common causes for cylinder 5 misfires on your 2022 GLE include worn spark plugs, especially if original equipment approaching 60,000 miles, failing ignition coil losing output voltage, clogged or leaking direct fuel injector, carbon buildup on intake valves reducing airflow, or decreased cylinder compression from valve or ring issues.
EQ Boost System Considerations
The 48-volt EQ Boost mild-hybrid system provides supplemental power and enables engine-off coasting and smooth restarts. While this system enhances efficiency, electrical issues could theoretically affect ignition or injection systems, though this is not a common cause of isolated cylinder misfires.
Diagnostic Process
Effective diagnosis requires analyzing misfire counter data, performing cylinder-specific component tests, and evaluating mechanical integrity. Mercedes-Benz XENTRY diagnostic equipment provides comprehensive access to these systems.