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:
- Ignition lockout, after three failed attempts, the control board enters a safety lockout and shuts down gas flow. A 30-60 second power cycle resets this.
- Gas supply interruption, the shutoff valve is closed, propane tank ran out, or a utility interruption cut gas briefly.
- Dirty or corroded igniter electrode, carbon buildup prevents the spark from jumping correctly across the gap.
- Failed thermopile/thermocouple or gas valve, the control signal that allows the gas valve to open has failed, or the valve itself is bad.
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?
This guide is for you if:
- 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 is NOT 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 is NOT 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 is 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), do not adjust connections
What is NOT 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:
- Confirm no gas smell near the heater
- Turn the heater power switch to OFF
- Wait 30-60 seconds for the control board to fully reset
- Turn the power switch back to ON
- Observe: the heater should attempt ignition within 30-60 seconds (you’ll hear the gas valve click, then igniter clicks)
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, do not 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 completely 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” is not.
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.
What the igniter electrode does: When the heater calls for heat, the control board sends voltage to the igniter, which creates a spark across the gap between the electrode tip and the burner. If carbon deposits bridge the gap or the gap is too wide, the spark either doesn’t jump or is too weak to ignite the gas.
How to inspect:
- Turn the heater power switch OFF
- Remove the heater cabinet access panel (typically 2-4 screws)
- Locate the electrode near the burner assembly, it looks like a ceramic-insulated spark plug tip
- Look for:
- Carbon buildup: Dark or black deposits on the electrode tip reduce spark reliability
- Incorrect gap: The gap between the electrode tip and burner should be approximately 1/8 inch (about 3mm). Wider gaps prevent spark; gaps that are too narrow can short out
- Cracked ceramic insulator: A crack in the white ceramic body means the electrode needs replacement (sparks will short through the crack)
- Green or white corrosion: Oxidation 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. Do not 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)?
The thermopile is a small device that generates a low-voltage electrical signal when heated by the pilot flame or ignition sequence. This signal is what “tells” the gas valve it’s safe to open and let fuel flow to the main burner. On most modern pool heaters, the thermopile (which generates more voltage than a single thermocouple) does this job.
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 is not 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: Does not display a specific ignition lockout code, but may show a PS (pressure switch) error if flow problems contributed to the ignition failure
For Raypak documentation, see Raypak heater support documentation{:target=“_blank”}. For Pentair, see Pentair pool heater ignition documentation{:target=“_blank”}.
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 the heater power switch to OFF. Wait 30-60 seconds for the control board to fully reset. Turn power back to ON. The heater should attempt ignition within 30-60 seconds. If the heater fires and holds, the lockout cleared. If the same error returns immediately, the underlying cause (gas supply, dirty igniter, or component failure) is still present.
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 is 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.