Heater shows E05 and shuts down; may occur after running for some time

Safety first: Turn OFF power to the heater. Water may be hot; use caution around plumbing.

• Compare displayed temperature: Note the temperature shown on the Poolworld control panel and compare it to an external pool thermometer. A large discrepancy suggests a sensor issue.
• Inspect sensor location: Locate the water temperature sensor on the inlet/outlet header. Ensure it is fully seated in its well and secured with the retaining clip.
• Check wiring: Follow the sensor cable back to the main control board. Look for cuts, abrasions, or rodent damage. Reseat the connector at the board.
• Clean contacts: If there is visible corrosion on the connector pins, gently clean with electrical contact cleaner and a soft brush, then reconnect.
• Test again: Restore power and see if E05 clears. If the error returns, the thermistor is likely out of range and should be replaced with a Poolworld-compatible water temperature sensor.

Warning: Do not operate the heater with a known faulty temperature sensor; overheating and equipment damage can occur.