Combustion and misfire diagnosis
A cylinder-specific misfire may come from ignition, injector delivery, air leaks, compression loss or valve timing. Identify which cylinders misfire and under what load or temperature. Inspect ignition and fuel trims, test coils and plugs where appropriate, and use compression or leak-down tests when the fault remains in the same cylinder. On direct-injection engines, carbon deposits and fuel pressure should be evaluated when symptoms support them. Do not replace all coils or injectors solely because of a misfire code.
Repair decisions and verification
Verify smooth operation at idle and under safe load, monitor misfire counters and confirm that catalyst-damaging misfires are no longer present.
Rough idle, hesitation or a flashing check-engine light may result from ignition, fuel, air leaks or mechanical engine problems. The applicable engine family changes considerably across C-Class generations.
How the problem should be evaluated
Review cylinder-specific faults and live engine data, test ignition and fuel operation, and investigate mechanical condition if a misfire persists. A coil or plug should not be replaced solely because the vehicle shakes.
Why the model and engine matter: The W204 C250 four-cylinder and C300 V6, later turbocharged W205 engines, and newer W206 electrified systems should not be treated as identical.
If you are experiencing this issue, contact Mich’s Foreign Cars in Hickory, NC at 828-324-6012. Provide the model, year, engine, warning text and when the symptoms occur so our service team can discuss an appropriate diagnostic visit.