Hayward Pool Heater Service Light On With Error Codes [Solved]

It’s a sore sight to see that the Hayward pool heater service light is on. The most common error codes in the Hayward pool heaters are the LO code, IF code, CE code, AO code, and BD code.

Keep reading this article to find out more about these Hayward pool heater error codes. We’ll discuss what each of these error codes means and how you can troubleshoot them step by step.

Hayward Pool Heater Service Light On With Error Codes [Solved]

The usual error code with the Hayward pool heater service light on for most people is the LO code. Let’s look at the issues that cause the LO error code and the other common error codes:

hayward pool heater LO error code

1. Hayward Pool Heater Service Light LO

The LO error code is the most common issue that keeps on happening with the Hayward H series heaters. It indicates the water pressure on the heater is too low. When the water pressure is low, the heater won’t fire up and it’ll display the error code.

While there are many reasons that could be causing the problem, the most usual one is that the filter gets dirty or clogged. The skimmer and pump baskets can also be plugged in and cause this issue.

Another reason that the heater will display the LO error code is when the heater is on but the pump is off. It’s completely normal and the LO error code will disappear when the pump is turned on.


How to fix the lO code on the Hayward heater? The first thing you should do is to backwash and rinse the filter. Nine times out of ten, a dirty filter will be the culprit behind this issue, and giving it a good wash will solve it.

If the LO error code doesn’t go away after washing the filter, open up the front cabinet and check for mouse bites on the wires.

Fix the wires if they are broken. If doing these things doesn’t solve the problem, you can read our ultimate guide on how to fix the LO code on Hayward pool heater or consult a technician to take a look at your heater and fix it.

2. Hayward Pool Heater Service Light CE

The CE error code stands for Communication Error. It’s displayed when the communication between the control module and the display board doesn’t work properly.

This problem can be caused if there is an issue with the ribbon cable that attaches to the display interface. Inspect the cable and check if it’s secure and that there are no burned or corroded areas.


The first step to solving this issue is to try cycling the power off and on. If it doesn’t do the trick, check that the plug is attached properly to the ICB. If there are burned areas, you’ll have to replace the display interface or keypad.

If all these steps don’t work, then chances are high that the ICB has gone bad. The last resort is to replace the control module and that should get rid of this error code and get your heater back to normal operating condition.

But, when you find the issue is still, then read our comprehensive guide on how to fix the Hayward pool heater CE error code by yourself.

3. Hayward Pool Heater Service Light IF

The IF error code in the Hayward pool refers to ignition failure. Here are the usual reasons that cause this error:

  • The gas shutoff outside the heater is closed.
  • The gas valve inside the heater is turned off.
  • Issues with the wiring of the Flame sensor and gas valve.
  • Incorrect gas static, manifold, and load pressures.
  • Faulty gas valve & malfunctioning flame sensor.
  • Damaged blower air inlet plate.
  • Blockage in gas orifices and burners.


Now that you know the wide range of causes that can cause this issue, follow these steps to fix this error code:

  • Make sure that the gas shutoff is open.
  • Turn on the gas valve inside the heater.
  • If any wire is broken or loose, fix it.
  • Apply the correct gas static, manifold, and load pressures.
  • Replace the gas valve if it’s faulty.
  • If there’s a 3″ flame sensor, replace it with a 5″ flame sensor.
  • Replace the blower air inlet plate.
  • Clean the gas orifices and burners and get rid of any cobwebs that may be present there.

Hopefully, doing the above fixing will bring your heater to functioning. But, if you find your Hayward is still showing the IF code on display, then read our complete solution guide to Hayward pool heater IF code. You will definitely get the solution.

4. Hayward Pool Heater Service Light AO

The AO error code represents that the blower vacuum switch is open. Here are the common reasons behind this AO error code:

  • Loose or broken wiring.
  • The wrong voltage at the voltage selector plug.
  • Resistance is out of range.
  • Faulty ICB.
  • The blower has gone bad.
  • Damaged blower vacuum switch.


Follow this Hayward pool heater troubleshooting guide to fix the AO error code:

  • Check the vacuum switch wiring, tubing, hose barb, and connections.
  • The voltage selector plug must be configured to the correct voltage.
  • Disconnect the blower from the ICB and check the resistance.
  • For models before 2010, the correct resistance is 8-9 ohms.
  • For models after 2010, the correct resistance is 4-5 ohms.
  • If the blower is out of resistance, it needs to be replaced.
  • Disconnect the blower plug from the control module.
  • Check the voltage by generating a call for heat.
  • The voltage should be 110-125 VAC across pins 1 and 2 of the inducer in the Control Board.
  • The control board needs to be replaced if this voltage is not present.
  • If the voltage is present and the blower is running fine, the blower vacuum switch must be replaced.

5. Hayward Pool Heater Service Light BD

This code is a cause of worry as it signals a bad board. Here are the common reasons behind the BD error code:

  • A blown-out fuse board.
  • Faulty Control Board
  • Faulty Wire Harness.


Here are the potential solutions to fix the BD error code:

  • Remove the FC4 fuse to measure continuity.
  • Pull the connector from P6 of the fuse board and make sure the voltage is 110-125 VAC across Pins 3 and 5.
  • Take off the P4 connector from the fuse board and check for voltage between 110 -125 VAC in pins 4 and 6.
  • Replace the fuse board if the voltage between 110 -125 VAC is present.
  • If the voltage is not present, the transformer needs to be replaced.
  • Disconnect the plug from the E10 connector of the control board and check for 110 -125 VAC in pins 1 and 3 of the wire harness.
  • If the voltage is present, the control board needs to be replaced.
  • If the voltage is not present, the wire harness must be replaced.


What are the Hayward pool heater lockout settings?

The maximum lockout settings for the pool mode are 90ºF and 104ºF for the Spa mode by default.

How to reset Hayward pool heater?

You can reset your pool heater lockout mode by using the keypad and changing the settings. You can change between the “Pool” and “Spa” modes by using the mode button.

Why won’t my Hayward pool heater ignite?

Insufficient water pressure, a low supply of gas, and clogged filters are the most common issues that keep the Hayward heater from igniting. Check the error codes to troubleshoot what is causing the problem.

Are Hayward pool heaters good?

Hayward pool heaters are highly reliable and durable. These heaters give you great energy savings and last for 7 to 10 years on average.


Now you know the most common error codes that cause the Hayward pool heater service light to stay on.

We hope this guide has helped you learn to troubleshoot these error codes and fix the issue with your pool heater. Drop a comment below if you have any questions about troubleshooting Hayward pool heaters.

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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