Safety first: Unplug the unit and close the inlet valve if opening the valve body.

Check brine level: Ensure the brine tank has sufficient water during brine draw so the brine line does not suck air.
Inspect brine connections: Tighten all brine line fittings at the control head and brine well to prevent air leaks.
Verify injector seals: Remove and inspect injector and associated O-rings. Replace any damaged seals.
Bleed air: After repairs, slowly open faucets throughout the home to purge trapped air from the lines.

Softener causes air spurting from faucets after regeneration.

Possible Causes