Display shows Err2 and regeneration stops mid-cycle

Safety first: Disconnect electrical power and place the Marlo softener in bypass before servicing the valve head. Depressurize by opening a nearby faucet.

Step-by-step checks:

• 1. Listen for motor operation: Restore power briefly and initiate a manual regeneration. If the motor hums but the cam does not turn, the gear train may be jammed. If there is no sound at all, suspect the motor or control board.
• 2. Inspect the drive motor and cam: Remove the control valve cover. Locate the Marlo drive motor mounted to the valve head. Check that the motor mounting screws are tight and that the cam gear is properly engaged with the rotor. Look for broken teeth, foreign objects, or hardened salt bridging the mechanism.
• 3. Manually index the valve: With power off, use a screwdriver on the manual advance slot (if provided on your Marlo model) to slowly rotate the cam through the cycles. If it binds or will not move, the rotor/seal pack may be seized and needs replacement.
• 4. Check cam position switch: Locate the cam position or micro-switch assembly. Inspect the actuator arm and wiring. Ensure the switch is being actuated by the cam. Test continuity with a multimeter while manually moving the cam.
• 5. Electrical tests: With power off, disconnect the motor leads and measure motor coil resistance. An open circuit indicates a failed motor. If the motor tests good but never receives voltage during a regen command, the control board motor output is likely faulty.

When to replace parts: Replace the Marlo drive motor if it is open or seized. Replace the cam position switch assembly if it does not change state when actuated. If mechanical parts move freely and the motor and switch test good, the Marlo control board may need replacement by a professional.