Ignition coils that deliver spark energy to each cylinder.
Coils convert battery voltage into spark energy. Weak coils can cause hesitation, loss of power or poor fuel use. Match coils by connector type, length and mounting style. Check spark plugs for wear because worn plugs increase coil load. Secure the coil firmly to avoid vibration. A strong coil output helps keep the engine smooth across different speeds.
A weak coil may not produce enough spark.
Worn plugs increase coil strain, so many workshops replace both.
Most coils do not require coding, but some vehicles use calibration steps.