Pump display shows E12 and pump shuts down intermittently

Safety: Turn off power and relieve system pressure before opening any filter or valves.

• Check filter pressure: Read the pressure gauge on the filter. If it is significantly higher than normal clean pressure (often 8–10 psi above), backwash a sand or DE filter or clean cartridge elements.
• Verify valve positions: Ensure return valves are not mostly closed. Fully open them and avoid throttling flow on the pressure side of the pump.
• Inspect for obstructions: Check for partially closed check valves, stuck heater bypass valves, or clogged heater internals that could increase head pressure.
• Listen for mechanical noise: Grinding or scraping from the pump may indicate internal drag from worn bearings or a rubbing impeller. Disassemble the wet end and inspect the impeller and diffuser for damage.
• Test at lower speed: Run the pump at a lower RPM and observe if E12 still occurs. Persistent overload at low speed suggests a mechanical or motor issue requiring component replacement.