Jandy Pool Heater FAULT-OPEN WATER SENSOR Error Code

Updated 2026-08-29 · review status: manual-verified Last verified: 2026-08-29

Quick answer

Open Water Temperature Sensor Water temperature sensor circuit is open (broken). Disconnected sensor, broken wire, failed temperature sensor. Check sensor wiring continuity. Ensure sensor is connected to PIB. Replace sensor if faulty.

Severity: high · DIY difficulty: intermediate

Safety

TBD - must be written per-code before publish

What FAULT-OPEN WATER SENSOR means

Open Water Temperature Sensor Water temperature sensor circuit is open (broken). Disconnected sensor, broken wire, failed temperature sensor. Check sensor wiring continuity. Ensure sensor is connected to PIB. Replace sensor if faulty.

Code meaning varies by series

  • JXi 200/260/400 & LXi 250/400: FAULT-OPEN WATER SENSOR: water temperature sensor circuit is open - faulty wiring/connection or failed sensor. Heater will not fire.

Causes, ranked

  1. 1. Faulty wiring or connection. occasional pro-only

    Check:

    Fix:

  2. 2. Failed water temperature sensor. occasional pro-only

    Check:

    Fix:

Parts & supplies for Jandy Pool Heater: filters, control boards, sensors, and common replacement parts.

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Sources

  • PoolDial error-code reference (manual-backed) — verified 2026-08-29
  • Jandy JXi Gas-Fired Pool and Spa Heater Installation & Operation Manual (Section 10.2 Service Diagnostic Messages, 10.3 Ignition Control LED Service Codes) — verified 2026-08-29
  • PoolDial Jandy JXi troubleshooting guide (fault-code table) — verified 2026-08-29