The 2022 Mercedes-Benz C-Class introduced the W206 generation with the M254 2.0-liter turbocharged 4-cylinder engine as the sole powertrain option for North American markets. When a P0305 diagnostic trouble code appears indicating a cylinder 5 misfire, this presents a diagnostic anomaly requiring investigation.
The P0305 Code Contradiction
P0305 translates to "Cylinder 5 Misfire Detected" in OBD-II terminology. However, the 2022 C-Class M254 engine contains only four cylinders numbered 1 through 4. This code appearing on your vehicle indicates a system anomaly rather than an actual cylinder 5 malfunction.
2022 C-Class Engine Configuration
The M254 engine in your C-Class features advanced 48-volt mild-hybrid technology, an electric auxiliary compressor for immediate boost response, and sophisticated engine management. Mercedes-Benz engineered this powerplant with cylinders 1-4 in an inline configuration with firing order 1-3-4-2.
Diagnostic Investigation Protocol
Proper diagnosis requires Mercedes-Benz XENTRY or STAR diagnostic equipment to analyze the actual misfire counters for each physical cylinder. The technician should verify whether the vehicle is experiencing real misfires on cylinders 1-4 while the system erroneously reports them as cylinder 5.
Common Causes for Code Anomaly
This unexpected code storage may stem from powertrain control module software issues requiring updates, ECU communication bus errors, electrical interference particularly from non-OEM accessories, or temporary voltage irregularities during 48-volt system transitions.