Hayward Pool Heater Error Codes [14 Easy Fixes]

There are quite a few Hayward pool heater error codes including the error codes AC, AO, bD, CE, EE, HF, HS, IF, IO, LO, PF, SB, SF, and bO.

We will take a look at the meaning of all of them in our article and provide you with simple solutions. Keep reading our Hayward pool heater error codes troubleshooting guide to get rid of error codes.

Table Of Contents

Hayward Pool Heater Error Codes [14 Easy Fixes]

Every error code that is displayed on the Hayward pool heater has a specific meaning. Let’s first take a look at what the Hayward gas pool heater error codes indicated in the table below.

Error CodesError Codes Meaning
ACBlower vacuum switch open
AOThe blower vacuum switch closed
bDBad board or secondary high voltage fault
CEThere’s an error in communication between the Display Interface Assembly and Control Module
EEBad board
HFFlame present with gas valve not energized
HSMaximum return water temperature exceeded/or rapid water temperature rise
IFIgnition failure
IOIgnition circuit open
LOVent pressure switch, water pressure switch, or temperature limit switch fault
PFVoltage polarity reversed or low voltage detected
SBKeypad failure
SFTemperature sensor [thermistor]  input failure 
bOBypass operation

1. Error Code AC

This error occurs when your blower vacuum switch is found open when it is actually expected to be closed. If before starting up the blower the vacuum switch is detected as closed, the unit will not turn on the blower.

Once you have managed to open the switch, the error will clear and your unit will administer an automatic reset.


Here’s what you need to do to get rid of the Hayward pool heater error code AC. It is a simple process. Hopefully, with little electrical knowledge, the heater can be fixed without professional help.

  • Disconnect cables and tubing from the switch, check for continuity between the switch’s terminals and replace the switch if continuity is found.
  • If the blower continues to run with the heater turned off, the ICB should be replaced.

2. Error Code AO

The AO code is basically the opposite of AC code. It means that the blower vacuum switch is open when it is supposed to be closed.

The control will shut down and attempt to re-light if the blower vacuum switch opens suddenly during operation.

The device will go into lockout mode with the blower operating if the switch is not closed after the blower starts. When the error is repaired, the system automatically resets.


To make the error code go away, follow the instructions below.

Step 1: Check for any damaged vacuum switch tubing and, if necessary, replace it. Inspect the wiring of the vacuum switch. Ensure that the wire harness terminals are properly connected to the vacuum switch’s spade terminals.

Step 2: Examine the wiring for the blower. Make sure the blower’s plug is securely secured to the control module.

Step 3: Disconnect the blower connector from the Control Module. Measure the resistance in the windings of the blower. Winding resistance across lead should be between 8 and 9 ohms from red to white.

The blower is malfunctioning if the measured values differ significantly from these levels. It should be replaced.

Step 4: Disconnect Blower connector from the Control Module. Set the heater to the Pool or Spa setting. To generate a call for heat, lower the set point temperature.

Step 5: Measure 120VAC along pins 1 and 2 during the pre-purge period. The control module relay is malfunctioning if 120VAC is not provided.

It should be replaced. If nothing has helped, you need to replace the blower vacuum switch.

3. Error Code bD

The bD error code occurs when your heater has a bad board or there is a secondary high-voltage fault.


To fix this issue you need to take care of the following components.

  • There is a fuse labeled ‘FC4’ in the fuse board. You need to make sure that it isn’t open.
  • Disconnect the plug from the Fuse Board’s P6 connector. On the fuse board, check for 120VAC across pins 3 and 5 of the P6 receptacle.
  • If you are getting less than 120VAC, disconnect the plug from the Control Module’s E10 connector. Measure the voltage across pins 1 and 3 of the Plug on Harness for 120 volts. Replace the Control Module if everything is in order. Replace Harness if it’s not working.
  • You may need to replace the transformer too if it is defective.

4. Error Code CE

The CE error code on the Hayward pool heater means that the control module and the display interface assembly aren’t communicating properly as they should. 


Here are the steps you need to take to get rid of this error code.

  • Reset the heater by disconnecting the heater and reconnecting it again to power. 
  • Examine the wires that connect the display to the computer. Ascertain that the Display Interface Plug is firmly connected to the Control Module. Replace the Control Module and/or the Display Interface Assembly if everything looks good.

5. Error Code EE

Hayward pool heater error code EE indicates a bad control board.


Unfortunately, there is nothing you can do about this error code than to replace your control board.

6. Error Code HF

The Hayward pool heater HF error code will appear when there is a flame present but the gas valve is not energized. 


Follow the instructions below to get rid of the HF error code.

  • Examine the unit with the sight glass to see if the flame is present. If not, ICB should be replaced. If there is a flame present, go to the next step.
  • Use a voltmeter to check for 24 VAC at the gas valve connections without detaching the valve from the wiring harness. If this is the case, ICB should be replaced. If not, it’s likely that the gas valve is broken and has to be replaced.

7. Error Code HS

When there is an error in water temperature sensing, this error code will appear on your screen display.


Check that the remote thermostat’s set point is at or below 104°F. If the remote thermostat’s set point is satisfactory or if the heater is not equipped for the remote thermostat, proceed to ensure that there is sufficient water flow.

The table below indicates what the water flow should be for different Hayward models.

After that, move on to test the heater’s temperature reading to the actual water temperature.

You will need a thermometer. Replace the inlet water temperature sensor if the difference is large.

8. Error Code IF

The IF error code stands for ignition failure. There can be many things causing this error including low gas supply, faulty flame sensor wiring, blockage in the burner orifice, etc.


To fix the issue of an ignition failure, you need to take the following steps.

  • Make sure that the main gas shutoff next to the heater is open and the knob on the gas valve within the unit is turned on.
  • Ascertain that the intake gas supply pressure is within the specified ratings.
  • Examine the flame detection circuitry. Ensure that the wire harness connectors on the flame sense and control module are firmly secured.
  • Examine the gas valve wiring. Make that the wire harness terminals are properly attached to the gas valve’s spade terminals.
  • During the ignition trial, measure the voltage across the gas valve. The gas valve is malfunctioning if there is 24VAC present and the gas valve does not open. Propane valve relay on the control module is broken if 24VAC is not supplied.
  • Check for blockages in gas orifices that could prevent gas flow. Burners should be removed and inspected for obstructions.

9. Error Code IO

This error code will appear on your screen when the igniter is open. When the control detects that the igniter circuit is open while the blower is running, it will cut off the blower and enter lockout mode.

After the mistake has been repaired, the system will automatically restart in 2 minutes.


Here is what you can do to get rid of the Hayward pool heater error code IO.

  • If the ignitor is broken, replace it.
  • Look for any problems with the ignition wiring. Also, make sure the ignitor plug is securely fastened.

10. Error Code LO

The LO error code will appear on your display when the limit string is open. When the limit string detects a low water flow, it opens.

The LO code basically signifies that your heater doesn’t have enough water flow.


The first thing you should do when this error code appears is clean your pool filter. Usually, a clogged pool filter is what is slowing down the flow rate.

Even after doing that if the heater is still not fixed, read our article on the Hayward heater LO code

11. Error Code PF

PF error code indicates an error in electrical supply wiring. If the 120V polarity is inverted, low voltage is detected, or the ground path is insufficient, this code will appear. Following the correction of an error, a reset occurs immediately.


Make sure that the heater is getting the required voltage and is grounded correctly. Also, ensure that the 120V polarity is not inverted. Correct it if needed.

12. Error Code SB

The SB error code occurs when your heater’s keypad has failed. 


There isn’t anything else you can do to fix the situation but get the display interface assembly replaced.

13. Error Code SF

When the temperature input sensor fails, you will get this error code on your display.


Examine the sensor wiring. Make sure the sensor is connected to the rear of the control module.

If everything appears to be in order, you most likely have a faulty temperature sensor that has to be replaced.

14. Error Code bO

The Hayward pool heater error code bO occurs during bypass operation. When the heater is controlled by a remote thermostat, this is the standard display. There is no requirement for service.

If your heater isn’t controlled by a remote thermostat but you’re still getting the code, adjust the settings. We’ll go over the adjustments you’ll need to make.


Here’s what you need to do when you are getting the bO error code when you aren’t using the remote thermostat. 

  • Put the heater into STANDBY mode by pressing the MODE key. 
  • Hold down the DOWN key while pressing and holding the MODE key. 
  • Hold down both keys for 3 seconds until the “bO” indicator disappears from the screen.


How do you clean the heat exchanger of a Hayward gas pool heater?

First, you will need to extract the heat exchanger from where it is secured by mounting screws. Using a soft-tipped brush, apply a degreaser to the heat exchanger. Allow the degreaser to loosen any remaining soot. Rinse the heat exchanger with a garden hose.

Can a pool heater get clogged?

Certain components of your pool heater may get clogged. One of the most common issues you will face is a clogged filter. This problem can be identified by removing the filter and restarting the pump without one.

Can a gas pool heater explode?

It’s highly unlikely. Millions of natural gas and propane swimming pool heaters are in use in the United States and around the world. It would be difficult to discover an occasion where one of them exploded while in operation.

How long do Hayward heaters last?

Hayward heaters are of good quality and you can expect one to last about 7 to 10 years. With regular maintenance, it can also last longer. Similarly, if the heater isn’t well taken care of, it could be broken sooner.

Do pool heaters give off carbon monoxide?

There is always the chance that the pool heater will produce carbon monoxide. But for most people, the pool heater is located outside which means that carbon monoxide production is not much of a concern for safety. It is still an environmental hazard. 


These are all the Hayward pool heater error codes. Error codes can cause a lot of anxiety. But you don’t have to worry.

Just follow our guide to understand the situation better. However, if you still have any confusion or questions regarding your

Hayward pool heater, we are more than glad to help you. Just leave a comment and we will get back to you ASAP. 

About David

David is a man who loves doing research and finding out the best solution to any type of heating appliance issues like heaters and fireplaces. Whenever he finds the perfect solutions to any issues of heating appliances after doing in-depth research, he loves to share them with his readers. In fact, his aim is to help his readers to fix the issues with their heating appliances easily.More about us .

Leave a Comment