P1019 (Freightliner): Cylinder 4 Ignition Coil Secondary Circuit Range/Performan… — what it means, the affected system and what to check before replacing parts.
The control unit has flagged the cylinder 4 ignition coil secondary circuit for operating outside of standard performance range. Manufacturer-specific definition; confirm applicability in the service information for the exact vehicle.
Affected system: Powertrain