E20 displayed and the Judo softener indicates a sensor bus or multiple sensor failure

Safety first: Disconnect power before unplugging sensors.

• Disconnect sensors one by one: Unplug each sensor (flow, hardness, salt level, leak, etc.) from the bus, then power up to see if E20 clears. The sensor that, when unplugged, clears the error is likely faulty.
• Inspect harness: Check the multi-core sensor cable for damage, moisture, or crushed sections.
• Replace faulty sensor: Install a new genuine Judo sensor for the identified faulty module.
• Board check: If E20 persists with all sensors disconnected, the sensor interface on the Judo main control board is likely defective and requires replacement.