LA MARZOCCO GS3 AV Error

Flow Meter Impeller

The impeller contains magnets that trigger the Hall effect sensor as it rotates; mineral scale or debris often jams the ceramic shaft, preventing rotation. When the impeller fails to spin despite water flow, the logic board receives zero pulses and triggers a timeout error. This is the most common mechanical failure point within the volumetric system.

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Flow Meter Sensor Cap

This component houses the Hall effect sensor that translates the impeller's rotation into electronic pulses. Heat soak from the steam boiler and moisture from the vacuum breaker can cause the internal circuitry to degrade or short, leading to intermittent or total signal loss even if the impeller is spinning freely.

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Group Head Gicleur (0.6mm)

The gicleur is a tiny orifice that regulates flow rate; if it becomes restricted by calcium deposits, the water velocity through the flow meter drops below the threshold needed to overcome the impeller's initial inertia. This results in the flow meter not spinning fast enough to satisfy the logic board's pulse-frequency requirements during the start of the brew cycle.

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