The 2020 Mercedes-Benz GLC X253 is predominantly powered by the M264 2.0-liter turbocharged 4-cylinder engine in GLC 300 variants. While the high-performance AMG GLC 63 offers a V8, standard models feature only four cylinders. A P0305 diagnostic code indicating cylinder 5 misfire requires special diagnostic consideration.
Analyzing the P0305 Code Anomaly
P0305 specifies "Cylinder 5 Misfire Detected," but if your 2020 GLC is equipped with the standard M264 4-cylinder engine, cylinder 5 does not exist. This code appearing on a 4-cylinder GLC indicates a diagnostic system irregularity rather than an actual fifth cylinder issue.
2020 GLC Engine Options Clarification
Standard 2020 GLC 300 and GLC 300 4MATIC models use the 4-cylinder M264 engine. Only the AMG GLC 63 variants have a V8 engine where cylinder 5 would exist. Verify your specific model before proceeding with diagnosis. Most GLC models on the road are 4-cylinder versions.
Diagnostic Approach for 4-Cylinder Models
For M264-equipped GLC models, the technician should verify whether actual misfires are occurring on cylinders 1-4 using Mercedes-Benz XENTRY diagnostics. The system should be checked for software updates, communication errors, or electrical issues causing erroneous code storage.
When Code May Be Valid
If your 2020 GLC is an AMG GLC 63 with the M177 V8 engine, P0305 is a legitimate code indicating cylinder 5 misfire and should be diagnosed accordingly with ignition, fuel, and mechanical testing specific to that cylinder.