IXI & JXi Heater Water Sensor Fault – Causes & Fixes

A water sensor fault on AstralPool IXI and Zodiac JXi gas pool heaters means there is a problem with the water temperature sensor or its wiring connection.

This fault may appear as an open water sensor fault or a shorted water sensor fault, and it prevents the heater from reading water temperature correctly.

A faulty water sensor can also cause incorrect temperature readings and result in the heater not heating correctly.

Common Causes of a Water Sensor Fault

• Damaged water temperature sensor
• Loose wiring or poor electrical connection
• Corroded sensor connection
• Sensor plug not seated correctly
• Fault on the control board

A failed water sensor can also contribute to overheating-related shutdowns such as a High Limit fault.

How to Fix a Water Sensor Fault

• Inspect the sensor wiring and plug connection
• Check for corrosion or visible damage
• Replace the faulty sensor if required
• Test the control board if the fault remains

If the heater is also showing unstable operation or repeated shutdowns, review the heater keeps turning off guide as well.

Common Heater Problems

• Heater Not Heating
• Heater Not Igniting
• Heater Keeps Turning Off

Related IXI & JXi Troubleshooting

• IXI & JXi Gas Heater Error Codes Guide
• High Limit Fault
• Check Flow Fault

When to Book a Heater Repair

Water sensor faults often require electrical testing and replacement parts, so professional diagnosis is recommended if the fault does not clear.

Book a Heater Service or Repair →

This article is for general information only. HeaterFix recommends all gas heater servicing, repairs and replacements be carried out by a qualified licensed gas fitter.