Pool Heater Ignition Failure: 4 Causes and What to Do
Pool heater ignition failure has four main causes: (1) ignition lockout from three consecutive failed attempts, (2) interrupted gas supply, (3) a dirty or corroded igniter electrode, and (4) a failed thermopile or gas valve that won’t open. Start with a 30-60 second power reset, it resolves the majority of ignition lockout events.
We put this guide together after reviewing the most common service call patterns, the lockout reset fixes things more often than most people expect. Start there before assuming a component has failed. This guide is part of our full pool heater troubleshooting guide. For pool equipment troubleshooting basics that covers more than just the heater, see that overview first if you’re new to pool maintenance.
Video guide
Video: “Why Won’t My Pool Heater Ignite?” by askthepoolguy
Quick answer, what causes pool heater ignition failure?
Gas pool heaters fail to ignite for four reasons, listed in order of how often we see each one:
First, if the ignition lockout activates after three failed attempts, a safety mechanism in the control board kicks in, shutting down gas flow for 30-60 seconds. Once this time period elapses, the system can be reset by cycling power. Next, ensure there has been no interruption to the gas supply due to a closed shutoff valve, an empty propane tank, or utility issues that briefly cut off the gas. Then, check the igniter electrode for any dirt or corrosion that could obstruct the spark from jumping across the required gap. Carbon buildup is often the culprit here. Finally, if none of these are the issue, a failure in either the thermopile/thermocouple or the gas valve might be to blame, as both components are essential for generating and transmitting the control signal necessary to open the gas valve.
Start with a power reset. Most ignition failures that appear suddenly are lockouts from a one-time gas supply hiccup, power off 30-60 seconds, back on, done.
Is this guide right for you?
:
- Your pool heater attempts to ignite (you hear clicking or gas valve sounds) but doesn’t light
- Your heater shows IGN FAIL (Raypak), E06 (Jandy), or a similar ignition error code
- Your heater was working recently and stopped igniting suddenly
This guide isn’t for you if:
- Your heater shows no signs of life at all, see heater won’t turn on at all for power and breaker diagnosis
- You smell gas near your heater, stop, evacuate, call your gas company’s emergency line immediately
- Your heater ignites and runs but doesn’t heat the pool, that’s a different problem (heat exchanger efficiency, heat loss, undersizing)
Safety first, before you diagnose
The important thing to understand: Ignition failure means the heater isn’t releasing gas without ignition. Modern gas pool heaters have a critical safety feature: if the heater fails to ignite, the gas valve closes automatically after three attempts. There’s no unburned gas accumulating around your equipment pad from an ignition lockout.
What is safe for homeowners:
- Checking error codes and looking up their meaning
- Resetting the ignition lockout with a power cycle
- Visually inspecting the igniter electrode through the access panel
- Checking the gas shutoff valve handle position (open vs closed), don’t adjust connections
What isn’t safe for homeowners:
- Opening any gas line connections or fittings
- Adjusting gas valve internals or gas pressure
- Replacing the gas valve
Step 1, reset the ignition lockout
A lockout reset fixes the majority of sudden ignition failures. Here’s why: when the heater fails to ignite three times in a row, the control board enters a safety lockout mode, shuts down gas flow, and displays an error code (IGN FAIL on Raypak, E06 on Jandy). This is a safety feature, not a component failure.
How to reset:
Check for any gas odor nearby the heater; then flip the power switch to OFF and pause 30–60 seconds before switching it back ON. Afterward, watch closely as the heater tries to ignite within that timeframe, listen for the click of the gas valve followed by the igniter.
If the heater fires and holds after the reset, the lockout was caused by a one-time gas supply interruption, a brief utility hiccup, an air bubble in the line, or running low on propane. No further action needed.
If the lockout returns immediately after the reset, the underlying cause is still present. Continue to Step 2.
Step 2, verify gas supply
Before assuming a heater component has failed, confirm gas is actually reaching the heater.
Check the gas shutoff valve at the heater: The handle should be parallel to the gas pipe (open position). If it’s perpendicular to the pipe, the valve is closed. Return it to parallel. This is a visual/mechanical check, don’t loosen or adjust any fittings.
Test other gas appliances: Turn on a gas burner on your kitchen stove or check your gas water heater. If those also won’t light, the issue is your gas supply, not your pool heater. Call your gas utility. If those appliances work normally, gas is reaching your home and the heater is the issue.
Propane users: If you have a propane tank, check the tank gauge. A tank below 20% can have insufficient pressure to reliably ignite the pool heater even if it’s not empty.
Before calling the heater a problem, also check pump is running before heater, some heater control boards won’t allow ignition if the flow switch detects insufficient water flow.
TABOO: Gas line connections and pressure verification require a licensed plumber. Checking the valve handle position is safe. Loosening fittings to “check for gas flow” isn’t.
Continue to Step 3 if gas supply is confirmed.
Step 3, inspect the igniter electrode
The igniter electrode is a spark plug-like component positioned near the burner. It creates the spark that ignites the gas. A corroded or incorrectly gapped electrode is the most common DIY-fixable cause of repeated ignition failure once a gas supply problem is ruled out.
Igniter Electrode Function: The control board supplies voltage to the igniter when heat is requested by the heater. A spark jumps across the electrode tip and burner gap. Carbon deposits blocking this path or an excessively wide gap prevent proper sparking, thus failing to ignite the gas.
How to inspect:
First, turn the heater power switch OFF. Next, remove the heater cabinet access panel by loosening 2-4 screws. Then, locate the electrode near the burner assembly. It resembles a ceramic-insulated spark plug tip. Look for signs of carbon buildup, which appear as dark or black deposits and can reduce spark reliability. Also check that the gap between the electrode tip and burner is approximately 1/8 inch (about 3mm). Wider gaps prevent proper sparking, while too narrow gaps may lead to shorting out. If you find a crack in the white ceramic body of the electrode, this indicates it needs replacement because sparks will short through any cracks. Finally, inspect for green or white corrosion on the electrode tip from humidity exposure.
Cleaning the electrode: Use fine emery cloth or light sandpaper on the electrode tip to remove carbon deposits. Don’t use water. Clean the tip until you see bare metal. Restore the gap to approximately 1/8 inch if it has been disturbed.
The pool heater igniter electrode requires a gap of approximately 1/8 inch (3mm) between the tip and the burner. Carbon buildup on the electrode is the most common DIY-fixable cause of repeated ignition failure, clean with fine emery cloth.
Igniter replacement: If the ceramic is cracked or the electrode is heavily corroded, replace the igniter. Parts typically run $50-$150 and the replacement is generally DIY-accessible if you’re comfortable with basic heater access. Match the part number from your model label to get the correct igniter for your heater.
After cleaning or replacing the electrode, reassemble the access panel and run through the Step 1 reset procedure.
Step 4, thermopile, thermocouple, and gas valve (pro territory)
If Steps 1-3 didn’t resolve the ignition failure, the problem is in the heater’s safety interlock chain: the thermopile/thermocouple or the gas valve itself.
What is a thermopile (or thermocouple)?
When heated by the pilot flame or ignition sequence, the thermopile produces a low-voltage electrical signal that activates the gas valve to allow fuel to reach the main burner. On modern pool heaters, where reliability matters, the thermopile, providing more voltage than a single thermocouple, undertakes this crucial function.
Signs of thermopile failure: The igniter sparks correctly (you hear the clicks and can see the spark through the access panel) but no gas ignites at the burner, no flame, no whoosh. The heater cycles through the ignition attempt and shuts down without the gas catching. A failed pool heater thermopile prevents the gas valve from opening, even when the igniter sparks correctly. Thermopile replacement costs $20-$60 in parts.
Thermopile testing: Requires a multimeter set to millivolts. A healthy thermopile typically reads 300-750 mV when hot. Below 200 mV usually indicates a weak or failing thermopile. This is a possible DIY test for confident homeowners familiar with multimeter use.
Thermopile replacement: Straightforward in terms of parts ($20-$60) but requires working near the burner and combustion area. Most homeowners will want a professional for this.
Gas valve failure: If the igniter sparks correctly and the thermopile tests healthy, the gas valve itself may not be opening. Gas valve diagnosis and replacement always require a professional. This isn’t a homeowner repair under any circumstances.
Cost of gas valve replacement: $100-$300 for the valve. Labor additional. Gas valve work requires a licensed plumber per NFPA 54 gas installation and safety standards{:target=“_blank”}.
Brand-specific error codes for ignition failure
If your heater is showing a specific error code, your brand page will have a more targeted walkthrough:
- Raypak: IGN FAIL / IF code, see Raypak IGN FAIL error for Raypak-specific reset procedure and model notes
- Jandy: E06 code, see Pentair heater ignition code and pool heater ignition failure for detailed steps
- Pentair MasterTemp: Doesn’t display a specific ignition lockout code, but may show a PS (pressure switch) error if flow problems contributed to the ignition failure
Check the Raypak heater support documentation at Raypak heater support documentation{:target=“_blank”} for troubleshooting and operation guides. For Pentair, visit Pentair pool heater ignition documentation{:target=“_blank”}. If your Raypak heater fails to start or loses prime due to a 20-psi pressure issue, ensure the pump is operating correctly and not tripping the breaker. A plugged drain can also cause water flow problems. Check for debris before you jump into repairs. Make sure your Raypak tank isn’t running dry, this could indicate an issue with your float switch or valve.
Easy to miss.
Easy to miss.
FAQ
Can I fix pool heater ignition failure myself?
Yes, for two of the four causes: ignition lockout (a 30-60 second power cycle) and a dirty igniter electrode (clean with emery cloth; $50-$150 to replace). Gas supply checks (valve position only) are also safe for homeowners. Thermopile and gas valve failures require a professional. Most sudden ignition failures resolve with the power reset, try that first.
How do I reset pool heater ignition lockout?
Turn off the heater power switch; wait 15 to 45 seconds for the control board to reset. Flip it back on. The heating element should attempt ignition within that time frame. If successful and stays lit, lockout has been cleared. Should the error recur instantly, inspect gas supply, igniter condition, or look for faulty components.
What does an ignition lockout mean on a pool heater?
Pool heater ignition lockout is a safety feature, not a component failure, the gas valve closes automatically after three failed ignition attempts to prevent unburned gas accumulation. The control board then displays an error code (IGN FAIL on Raypak, E06 on Jandy) and stops further ignition attempts until manually reset. There’s no active gas hazard during a lockout.
How much does it cost to repair pool heater ignition failure?
Igniter cleaning: free. Igniter replacement: $50-$150 in parts (often DIY). Thermopile replacement: $20-$60 parts plus $75-$150 labor if you hire a pro. Gas valve replacement: $100-$300 parts plus labor. Requires a licensed plumber. Annual professional service ($100-$175) that includes igniter inspection catches most electrode issues before they cause a lockout.
Why does my pool heater ignition keep failing?
Recurring ignition failure usually points to one of two things: a consistently dirty igniter electrode (fix: clean or replace) or an intermittent gas supply issue (fix: check propane levels, verify no utility fluctuations). If the lockout returns reliably within a few heating cycles after resetting, schedule a professional inspection, recurring lockouts can indicate a thermopile that’s weakening before full failure.