The Jandy JXi is a reliable, well-engineered gas heater — but like all modern heaters, it has an extensive fault code system that can seem cryptic on site. This guide covers every JXi error code you're likely to encounter, what each means in plain language, and what to check first. Bookmark it and use it alongside PoolLens for fast on-site diagnosis.
| Code | Description | First Action |
|---|---|---|
| E01 | Ignition Failure | Check gas supply, igniter, flame sensor |
| E02 | High Limit Fault | Check flow rate, dirty filter |
| E03 | Water Temperature Sensor Fault | Check sensor connector and resistance |
| E04 | Stack Flue Temperature High | Check flow, scaling, exchanger |
| E05 | High Limit Sensor Fault | Test and replace high-limit sensor |
| E06 | Pressure Switch Open | Check blower, pressure switch hose |
| E07 | Low Water Flow | Clean filter, open valves, check pump |
| E08 | Inlet Water Sensor Fault | Check sensor resistance and connector |
| E09 | Outlet Water Sensor Fault | Check sensor resistance and connector |
| E10 | Stack Flue Sensor Fault | Check stack sensor and wiring |
| E11 | Low Gas Pressure | Check gas supply pressure with manometer |
| E12 | Rollout Safety Fault | Call licensed technician — combustion issue |
| E13 | AquaLink Communication Fault | Check RS-485 wiring and addresses |
The JXi tried to light the burner and failed. The unit makes 3 ignition attempts, then locks out. Unlike some brands, the JXi uses a hot surface igniter (HSI) and a flame rod sensor. Common causes: failed HSI (measure resistance — should be 40–90 ohms cold), dirty flame rod (clean with fine steel wool), low gas pressure (minimum 4" WC natural gas / 11" WC propane), or a failed gas valve. Reset by holding the temperature down button for 5 seconds, or power-cycle at the breaker after fixing the root cause.
The JXi uses a differential pressure switch to confirm adequate flow — not a simple paddle switch. This makes it more accurate but also means the fault can be triggered by slightly lower-than-normal flow that wouldn't trip a traditional flow switch. Common triggers: a filter that needs backwashing, partially closed valve, undersized pump, or a clogged heat exchanger. Measure flow rate with a flow meter if possible. The JXi requires a minimum of 20 GPM for the 150K model up to 50+ GPM for the 400K model.
Temperature inside the heat exchanger exceeded the safety threshold. Almost always caused by low flow — address E07 causes before testing the high-limit sensor itself. The sensor is a non-adjustable snap disc located on the heat exchanger header. Test by measuring continuity at room temperature (should be closed). If the sensor opens below 135°F, replace it.
E12 is a rollout safety fault. A rollout condition occurs when flames "roll out" of the combustion chamber — they are not contained within the burner assembly. This is a combustion failure that creates a fire and carbon monoxide hazard. Do not attempt to reset and restart the heater. Do not try to diagnose combustion issues without specialized training and equipment. Call a licensed gas technician.
E12 (Rollout) is a life-safety fault. Do not bypass, reset, or restart the heater until a qualified gas technician has inspected the combustion system. This code indicates active fire or CO hazard potential.
For most fault codes (E01–E11, E13):
JXi tip: The fault code history can be accessed on units with the "FaultLog" feature by pressing Mode and Temperature simultaneously. This shows the last 10 faults — invaluable for diagnosing intermittent problems.
| Model | BTU Rating | Min Flow (GPM) | Max Flow (GPM) |
|---|---|---|---|
| JXi 150 | 150,000 | 20 | 125 |
| JXi 200 | 200,000 | 25 | 125 |
| JXi 260 | 260,000 | 30 | 125 |
| JXi 400 | 400,000 | 45 | 125 |
PoolLens includes the full Jandy JXi, LRZ, and Legacy error code database. Look up any code the moment you arrive — no signal needed.
Open PoolLens Free →E01 (ignition failure) and E07 (low water flow) are the most frequently seen JXi codes in the field. E01 is typically a gas supply or igniter issue; E07 is almost always a filter or valve problem.
Press and hold the temperature down button for 5 seconds to clear most fault codes. For a hard lockout after repeated E01, you may need to power-cycle at the breaker.
E13 on the Jandy JXi is an AquaLink communication fault — the heater has lost communication with the AquaLink RS or iAqualink automation system. Check the RS-485 wiring and address settings.
Yes. The JXi is compatible with salt water pools. Maintain calcium hardness above 200 ppm and pH between 7.4–7.6 to prevent accelerated heat exchanger corrosion.
The JXi uses a differential pressure switch (not a paddle-type flow switch) located near the inlet/outlet headers. It senses pressure difference across the heat exchanger to confirm adequate flow.