Display shows “Err 8” and the system will not accept new programming or appears locked.

Safety first: No internal electrical work is required for basic checks; unplug only if removing covers.

• Check for keypad lock: Some Fleck controls allow keypad lock. Follow the manual to unlock (often a specific button sequence).
• Enter installer mode: Use the installer code or sequence to access advanced settings. If unknown, consult the original installer or Fleck documentation.
• Factory reset: Perform a full reset to clear lockouts, then reprogram all parameters.
• Replace control if unresponsive: If the keypad and programming remain locked after reset attempts, the control board may be defective and require replacement.