Heater stops heating and displays E02; unit may attempt to restart but trips again.

Safety first: Turn off power at the isolator and allow the heater to cool for at least 30 minutes before inspection. Do not bypass safety thermostats.

• Check water flow: Confirm the circulation pump is running and that inlet/outlet valves to the heater are fully open. Clean filter and baskets to ensure strong flow.
• Inspect for kinks or blockages: On above-ground or flexible pipe installations, check for collapsed hoses or closed valves that could restrict flow.
• Descale elements (if accessible and recommended by Elecro manual): Remove the heater cover, isolate water, and inspect the titanium heating elements for heavy scale. If scale is present, follow Elecro’s procedure for descaling or replace the element assembly.
• Reset high limit: Some Elecro models have a manual reset high limit thermostat on the heater body. After cooling, press the reset button if present. If it trips repeatedly, investigate flow and scaling issues.
• Sensor check: Inspect the high limit sensor wiring to the control PCB for damage or loose connections.

Persistent E02 after restoring flow and checking for scale indicates a likely faulty high limit thermostat or sensor that should be replaced.