N63 and S63 Engine: High-pressure Fuel Injector Replacement Procedures. The customer complains that one of the following scenarios has been encountered while operating the vehicle: * During a cold start in the morning, the engine runs very roughly and the Service Engine Soon lamp is illuminated. * During a hot start, the engine runs very roughly and the Service Engine Soon lamp is illuminated. While driving or idling, the engine will misfire and the Service Engine Soon lamp is illuminated. * Various misfire faults are stored in DME fault memory. CAUSE An internal failure of the high-pressure fuel injector can lead to incorrect operation.