DIY Error Codes

Jandy JXi gas pool heater Fault HIGH LIMIT

Water in the heater got too hot, or a limit switch failed, so the gas valve closed. Jandy's first owner check is the vent.

Check the vent for obstructions. If HIGH LIMIT returns, call a qualified technician.

Start the fix →When to call a pro ↓
Full answer & models

Jandy JXi HIGH LIMIT means water in the heater exceeded the internal limit or a limit switch failed. Check the vent for blockage; call a pro if it returns.

Applies to: JXi 200JXi 260JXi 400
Also searched as: Jandy heater FAULT-HIGH LIMIT, Jandy JXi high limit, Jandy pool heater high limit fault, Jandy heater high limit switch

Gas appliance. Owner checks only; Jandy says a qualified professional service technician must do all service.
Why
Jandy, what to do if you smell gas: immediately switch off main gas supply; do not try to light any appliance; do not touch any electrical switch; do not use any phone in your building; immediately call your gas supplier from a neighbor's phone and follow the gas supplier's instructions; if you cannot reach your gas supplier, call the fire department. Installation and service must be performed by a qualified installer, service agency or the gas supplier. Jandy: ELECTRICAL SHOCK HAZARD. This heater contains wiring that carries high voltage. Contact with these wires may result in severe injury or death. Jandy servicing safety: service procedures can be hazardous because they involve fuel gas, electricity, moving parts and procedures which require testing or temporary bypass of safety controls, so the heater must be serviced only by a qualified professional service technician. Improper installation or maintenance can cause nausea or asphyxiation from carbon monoxide in flue gases which could result in severe injury, or death.

What HIGH LIMIT means

Water in the heater got too hot, or a limit switch failed, so the gas valve closed. Jandy's first owner check is the vent.

More detail
Jandy's JXi manual (Section 10.2, Service Diagnostic Messages, p. 47) lists "FAULT-HIGH LIMIT" with two possible causes: water temperature in the heater exceeds the internal limit, or a limit switch fault. Section 1.8 (p. 7) says the high limit switches, one at the heat exchanger first pass (135 °F / 57 °C) and one at the heat exchanger outlet (150 °F / 65 °C), close the gas valve and stop combustion if either senses excessive temperature.

5-minute checks

Fix it step by step

Step 1 of 3

  1. Inspect the vent for blockage

    • 5 min
    • None
    • Caution

    Safety: Gas appliance. Owner checks only; Jandy says a qualified professional service technician must do all service.

    Jandy's first listed remedy.

    More detail

    Inspect the vent for blockage.

    Jandy remedy (p. 47): inspect vent for obstructions or blockages. Look only. Jandy: improper maintenance can cause asphyxiation from carbon monoxide in flue gases. Do not take the vent apart.

    Did the code clear?

  2. Indoor heaters: check the vent pipe for nests

    • 5 min
    • None
    • Caution

    Safety: Gas appliance. Owner checks only; Jandy says a qualified professional service technician must do all service.

    Birds, insects or rodents can block it.

    More detail

    Indoor heaters: check the vent pipe for nests.

    Jandy remedy (p. 47): for indoor installations, check the vent pipe for bird, insect or rodent activity that could cause a blockage. If you find a blockage, have a technician clear it. Look only. Jandy: improper maintenance can cause asphyxiation from carbon monoxide in flue gases. Do not take the vent apart.

    Did the code clear?

  3. Call a qualified service technician

    • Decision
    • None
    • Pro decision

    Stop here and book a qualified technician.

    More detail

    Call a qualified service technician.

    Jandy's remaining remedy for HIGH LIMIT (p. 47) is to replace the switches, which is technician work. Jandy (Section 11, p. 48): call a qualified service technician to perform all service and repairs on the heater. Do not open the heater cabinet yourself.

    Still showing HIGH LIMIT?Need a pro → call a pro

Code cleared. Nice work.

Watch the display for a day to make sure it stays clear.

Back to top

Fixed after any step? Watch the display for a day to make sure it stays clear. Still HIGH LIMIT after step 3? call a pro.

Call a pro if…

  • You smell gas (switch off the main gas supply if you can, then call your gas supplier from a neighbor's phone).
  • HIGH LIMIT keeps coming back after the owner checks.
  • Anything that needs the heater cabinet opened, wiring checked, or gas pressure tested.

FAQ

What does HIGH LIMIT mean on a Jandy JXi?

Per Section 10.2 (p. 47): water temperature in the heater exceeds the internal limit, or a limit switch fault.

At what temperature do the JXi high limit switches trip?

Jandy's manual (p. 7) lists one switch at the heat exchanger first pass, 135 °F (57 °C), and one at the heat exchanger outlet, 150 °F (65 °C). If either senses excessive temperature, the gas valve closes and combustion stops.

Source: Jandy JXi Gas-Fired Pool and Spa Heater Installation & Operation Manual (H0574300 Rev M), Section 10.2 Service Diagnostic Messages (p. 47); Section 1.8 (p. 7); safety, pp. 1, 32, 38 and 48. Written by the DIY Error Codes team. Updated 2026-10-16. DIY Error Codes is independent and not affiliated with or endorsed by Jandy.