Irritrol/HR 6100 "2A" Error: Valve 2 Solenoid Short

The "2A" flashing error on a Hydro-Rain/HR 6100 (often badged Irritrol) indicates a current overload on zone 2—typically a shorted solenoid or wire fault on that specific zone.

Immediate Diagnosis

1. Disconnect zone 2 wire at controller terminal.
2. Run a manual cycle. If "2A" clears, fault is in zone 2 field circuit.
3. At valve box, disconnect zone 2 solenoid leads.
4. Measure solenoid resistance: should be 20–60 Ω. Near 0 Ω = shorted coil.
5. Check wire continuity from controller to valve.

Controller Identity Note

The HR 6100 was manufactured by Hydro-Rain (later acquired by Irritrol). It does not typically display alphanumeric errors like "2A"—this suggests either a later firmware version or a different controller (e.g., Irritrol Total Control). Verify model number on enclosure label.

Fix

• Shorted solenoid: Replace ($15–$20).
• Nicked wire: Repair with waterproof splice.
• Water in splice: Re-splice with gel-filled connectors.

If All Zones Show Errors

Common wire shorted to hot wire, or controller output driver failed. Disconnect common at controller; if errors persist, controller needs replacement.