The computer sees a fault in the circuit of coil A, usually the coil for cylinder 1. The driver may notice a misfire, shaking and weak power.
Likely causes, most common first
- Faulty ignition coil
- Damaged wiring or connector
- Poor coil ground
- Worn spark plug stressing the coil
Parts usually involved
- Ignition coil
- Spark plug
- Coil connector
Test before you replace
Swap the coil with another cylinder and check power and control signal at the connector.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.