Pool Heater Won't Ignite

The heater tries to light the burner, fails, and locks itself out — here's what typically stops a gas pool heater from igniting, before you've even found your model's specific code.

What's usually going on

Every gas pool heater sold under the three brands covered here handles a failed light the same basic way: the control makes a set number of attempts to establish a flame — usually three — and if none of them succeed, it locks out the gas valve rather than keep dumping unburned gas into the burner compartment. What causes those failed attempts falls into three buckets. The first is gas supply: a valve that isn't fully open, a propane tank that's empty or reading low, or gas pressure that's too low for the heater's BTU rating. The second is the hardware that actually senses and starts the flame — a flame-sensing rod that's corroded, misaligned, or coated in soot, or an igniter that's weak, cracked, or has simply worn out. The third is electronic: a failing ignition control module or gas valve that no longer fires reliably even when everything upstream is fine. Because the lockout behavior looks identical across brands from the outside — the heater tries, fails, and gives up — the fastest way to narrow it down is to check the cheap, external causes first before assuming a part has failed inside the cabinet.

Codes that show this symptom

• Hayward IF — Ignition Failure
• Pentair ERR IGN — Ignition control fault
• Raypak IGN — Ignition failure
• Raypak ILO — Ignition Lockout after repeated failed attempts

Full code lists by brand: Hayward, Pentair, Raypak.

Checks that apply regardless of brand

1. Confirm the gas supply valve to the heater is fully open, and if you run on propane, that the tank isn't empty or dangerously low.
2. Clear the lockout — press the reset or "heater off" button your model uses — and let it attempt to light again.
3. Check whether any other gas appliance on the same line (water heater, furnace, range) is working normally; if it is, the supply itself is probably fine and the fault is inside the pool heater.
4. If you can safely see into the burner compartment during a light attempt, look for a spark or an igniter glow — nothing visible points at the igniter rather than the gas supply.