Display shows “Err 02” and regeneration stops mid-cycle

Safety: Disconnect power and place the Sterling softener in bypass before servicing the valve head.

Diagnostic and fix steps:

• 1. Locate the position sensor: On most Sterling Water softeners, a small micro-switch or optical encoder is mounted near the valve cam or rotor. Remove the control cover to access it.
• 2. Check mechanical alignment: Verify the cam or rotor tab that actuates the switch is intact and properly aligned. If the cam is loose on the shaft, tighten or replace it.
• 3. Test the switch/encoder: With power still OFF, disconnect the sensor harness. Use a multimeter in continuity mode to check the micro-switch operation while manually rotating the cam. For optical encoders, check for broken housing or contamination.
• 4. Inspect wiring: Follow the harness from the sensor to the control board. Look for broken insulation, corrosion at connectors, or loose pins. Clean and reseat connectors.
• 5. Clean sensor area: Remove any iron sludge, salt dust, or moisture around the sensor that could interfere with operation.
• 6. Replace if defective: If the switch does not change state or the encoder is physically damaged, replace the valve position switch/encoder.
• 7. Reset and test: Restore power, take the unit out of bypass, and initiate a manual regeneration. If Err 02 persists, the main control board may not be reading the sensor correctly and may require replacement by a technician.