Hayward Pool Heater Reset: How to Clear Fault Codes

Quick Answer

Press the Mode button on the control panel to cycle through to Standby, then back to your desired temperature setting. For a full system reboot, flip the dedicated heater breaker off for sixty seconds and then back on to clear the logic board.

Most of the time when I get called out for a Hayward reset, the heater's fine. It's the pool system around it that caused the lockout. Ignore it long enough and you're looking at a cracked heat exchanger from the unit cycling on and off a hundred times trying to light. That's a $800+ repair instead of a $0 filter cleaning. Don't ignore it.

HaywardPoolheater85% DIY Success

How to Reset Your Hayward Poolheater

Nine times out of ten, these heaters trip because of a dirty pool filter or a closed valve. I literally just did three of these last week, all the same thing. A reset clears the Service light and gives the ignition control a fresh start, but if your flow's bad it'll be right back on in an hour. Cost to reset? Zero. Cost to ignore it and crack your heat exchanger? Ask me how I know.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Ignition Failure (IF)45%

Low Flow (LO)30%

High Limit Trip15%

Control Board Glitch10%

Symptoms You May Notice

The orange Service light is on solid and won't shut off even after the water hits the set temperature
Display is flashing IF repeatedly and you can actually hear it attempt to fire three times, click-click-click, then just quit
LO code shows up on the display, usually first thing in the morning when the pump kicks on after sitting overnight
Fan runs for 30-40 seconds, you can hear it spinning, but there's no igniter clicking and you never smell gas
The whole control panel is frozen on the last set temp and none of the buttons do anything when you press them

Tools Required for Diagnosis

Phillips #2 screwdriverFlathead screwdriverDigital multimeterFlashlight or headlampGarden hose (for backwashing or rinsing filter)Pressure gauge (if pool system doesn't already have one installed)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Frequently Asked Questions

Why does my Hayward pool heater keep saying Service?

Service is just a general alert that a safety limit tripped. It doesn't tell you what the actual problem is, which is super annoying. In my experience the two most common culprits are LO code (low water flow, usually a dirty filter) and IF code (ignition failure, usually air in the gas line or a worn flame sensor). Resetting clears the light, but if you didn't fix whatever caused it, it's coming back. I'd say 70% of the Service calls I go on are solved with a filter cleaning and a reset. The other 30% actually need parts.

How many times can I reset the heater before it's a problem?

Two, maybe three times in a day before you need to stop and actually diagnose it. The heater's locking out for a reason. If it keeps tripping the same fault, every reset you do is making the hot surface igniter work harder and shortening its life. Those igniters are about $40-60 bucks and they're wear items, but you don't want to burn through one in an afternoon because you kept forcing resets. More importantly, if there's a gas issue and you keep resetting, you're dumping unburned gas. That's not a situation you want.

Will resetting my Hayward heater fix the LO code?

It'll clear it off the screen, yeah. But it won't fix the actual problem, which is that your pressure switch isn't seeing enough water movement to feel safe letting the burner run. The fix for LO is always on the water side: clean the filter, empty the pump basket, check that all your valves are fully open, and on a variable speed pump, bump your RPMs up. On Hayward H-Series heaters the minimum flow requirement is usually around 20-40 GPM depending on your BTU model. If your pump can't hit that, the code's coming back no matter how many times you reset.

What does the IF code mean on a Hayward heater?

IF is Ignition Failure. The board tried to light the burner three times in a row and the flame sensor never confirmed a flame. So it locks out to keep gas from building up. Most common causes I see are air in the gas line on first startup of the season, a dirty or corroded flame sensor rod (easy $15 fix if you're comfortable with it), low gas pressure from the utility, or the hot surface igniter starting to fail. A reset lets it try again. If it fails three more times, it'll lock out again and show IF again.

Is there a secret reset button inside the heater cabinet?

On the newer digital H-Series models, no. There's no physical reset button hiding in there. Everything goes through the keypad or the breaker. But on the older millivolt and standing pilot models, yes, actually. You'll find red reset buttons on the high-limit switches, usually two of them, mounted on the header pipes near the top of the heat exchanger. They pop out when they trip. You just push them back in. If yours is an older model without a digital display, that's probably what you need. Pop the cabinet door and look for small red buttons near the water pipes.

Models Known to Experience RESET Errors

This repair applies to most Hayward poolheaters with this error code. Common model numbers include:

H150FDP, H200FDP, H250FDP, H300FDP, H400FDP, H150FDA, H200FDA, H350FDN, H400FDN

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 17, 2026