E18 error and the unit indicates a bypass valve position fault (on models with electronic bypass feedback)

Safety first: Turn off water if you need to remove the bypass assembly. Expect some water spillage.

• Check bypass handle: Verify the bypass handle is fully in the SERVICE position, not partially between BYPASS and SERVICE.
• Cycle bypass: Move the bypass from SERVICE to BYPASS and back several times to free any stiffness. Do not use excessive force.
• Inspect sensor (if fitted): On models with a bypass position sensor, ensure the sensor is correctly aligned and its wiring is intact.
• Re-seat bypass: If recently serviced, confirm the bypass assembly is fully inserted and O-rings are correctly seated in the valve body.
• Replace bypass assembly: If the valve is cracked, leaking, or will not move smoothly, replace the Aqua Dial bypass valve assembly.