Hayward Pool Heater Error Codes [Full List + Reasons + Solutions]

Hayward pool heater has 13 distinctive error codes to notify several flaws and malfunctions going through the unit. The main error includes bD, EE, CE, IO, Sb, SF, HS, HF, bO, LO, IF, AC, and AO. 

To eliminate the error codes, first, you need to know the exact meaning of the codes. Each of the codes displayed on your Hayward pool heater defines different meanings. 

hayward pool heater error codes

Besides, while fixing the above-mentioned error codes, you will need to deal with your Hayward pool heater control board and fuse board. It’s a must.

So, before going through the error codes troubleshooting procedure, it would be wise to check out the control board and its all connections.

hayward pool heater control board diagram

Hopefully, you could already be acquainted with the control board. Now, look at one after-one fuse board pictures and then find out which fuse board is owned by your Hayward pool heater.

Then be familiar with all the connections of your fuse board. It will definitely simplify your error codes troubleshooting job.

hayward pool heater fuse circuit board connection diagram
hayward pool heater fuse board configuration diagram november 2010 forward
hayward pool heater fuse board configuration diagram through october 2010

Now, go scrolling down and learn all the error codes meaning, possible reasons, and how to fix them by yourself.

Quick Indication For All Hayward Error Codes

Before moving to the troubleshooting procedure, let’s have a glimpse at the below table, highlighting all error codes of your pool heater with the exact indication.

Error CodesError Indications
bDBad board or secondary high voltage fault
EEBad board
CECommunication error between Display Interface Assembly and Control Module
IOIgnition circuit open
SbKeypad failure
SFTemperature sensor [thermistor]  input failure 
HSMaximum return water temperature exceeded and/or rapid water temperature rise
HFFlame present with gas valve not energized
bOBypass operation
LOVent pressure switch, water pressure switch, or temperature limit switch fault
IFIgnition failure
ACThe blower vacuum switch closed
AOBlower vacuum switch open

Hayward Pool Heater Error Codes [Reasons + Solutions]

While fixing the above-mentioned error codes, the need for a detailed solution guide is obvious. Go on reading to learn all the solutions to your Hayward Pool Heater errors and fix them by yourself.

1. Error Code ‘bD’

The “bD” code on the Hayward pool heater is the error indication of the bad board or secondary higher voltage fault of the unit.

The error is related to the blown-out FC4 fuse. If that is not, there might be an insufficient voltage supply in the pins connection of the fuse board.  

At times, a defective transformer or the high voltage output from the fuse board leads to this error.

How To Fix:

To fix this issue you need to measure the continuity between the fuse pins. Follow the below steps:

Step 1: First locate the FC4 fuse labeled on the fuse board. You have to make sure that the fuse is not open.

Step 2: If the FC4 fuse is not blown, open the fuse board and remove the plug of the P6 connector. Measure the voltage across pins 3 and 5. It should give a reading of 110-125 VAC.  

Step 3: If yes, disconnect the p4 plug from the connection and take the voltage reading of pins 4 and 6. Here you will also get reading for 110-125 VAC.  

Step 4: In case you are getting the right voltage in both cases, it’s a must say that the fuse is blown and you need to replace it. Otherwise, move forward to check the transformer.

Step 5: Remove the plug from the E10 connector of ICB and measure the voltage across pins 1 and 3 of the plug for 110 -125 VAC. Replace the ICB if the voltage is present. In case not, replace the wire harness.

2. Error Code ‘EE’

EE error code appearing on the Hayward pool heater display tells the bad board of the unit. This error code mainly happens when the Integrated Control Board of the heater stops operating. 

hyward pool heater icb

How To Fix:

Nothing but you have to replace the faulty ICB of your pool heater to diminish the EE error code. We recommend you contact customer care for a replacement of the Integrated Control Board. 

3. Error Code ‘CE’

When there is a communication error between the control and display interface assembly, the heater control unit shows the CE code within 3 s.

Inconsistency in the power supply or the power outage is the root reason behind this code. Otherwise faulty wiring or cable connection is the culprit. 

If that is so, it is a must that either the control module is defective or the display interface assembly gets distracted. 

 hayward pool heater display interface assembly distracted

How To Fix:

Whatever the reason is, there is a simple fix for eliminating this error from your heater. Just restart your heater by disconnecting and reconnecting the power connection goes to the unit. 

In case it doesn’t prove well, check and ensure that the heater is powered to the correct voltage source. Then, inspect the wiring connection of the board. Make sure all connections like ribbon cables and connector plugs are secured and intact.

Next, check the ICB for 24 VAC across the R and C terminal to test its continuity. Replace if needed. Same as replacing the bad display interface assembly as well. Contact any certified distributor for the replacement part. 

Generally, the Digital Display Boards cost about $229 – $249 at Amazon. The Main control boards can be found at $249.

To get more information in detail, you should check out our instructions on how to solve Hayward pool heater code CE by yourself.

4. Error Code ‘IO’

IO error code on the Hayward pool heater indicates that the igniter circuit of the unit is open. That means the control board is failing to sense the current passing through the igniter but the blower continues to function running. 

Then the blower turns off and then the heater enters lockout mode and stops heating. It can happen because of faulty wiring or a misplaced connection. Or, the igniter itself is defective and leads to this error. 

How To Fix:

First off, inspect the wiring on the igniter and ensure all are intact. Also, the igniter plug should be attached firmly to the control board.

hayward pool heater igniter plug to the control board

If still, the same error, go for checking the continuity of the igniter. A well-working igniter will give a reading of 8-25 ohms between 20°- 140° F. In case the igniter resistance is out of this range, replace it. 

5. Error Code ‘Sb’

The Sb on your Hayward heater is the keypad failure error. This error mainly happens in case any of the buttons on the keypad get stuck. 

hayward heater keypad failure

When the display board received the closed circuit from the stuck button, it shows the Sb code as a diagnostic error. In most cases, there could be another internal problem with the keypad.

How To Fix:

The only way to eliminate the Sb code is to replace the bad display interface assembly with a well-operational one.  

6. Error Code ‘SF’

Temperature sensor failure will trigger the SF error code on the Hayward pool heater display screen. It might be because of faulty wiring or a loose connection to the ICB. Or, the sensor itself is defective and fails to get the data from the circuit board. As a result of this fact, the heater shows the SF code as an alert.

How To Fix:

  • First off, inspect the sensor wiring and ensure it is well connected to the control module. 
  • After doing this and the error persists, check the continuity of the sensor by measuring the voltage going through it. 
  • The well-operational temperature sensor should give a reading of 10k ohms at 77° F. If not, replace the defective temperature sensor. 
  • At times, you might need to replace the bad ICB to get back the heater from this error.

However, you should go through our complete guideline on how to fix Hayward Pool Heater 5F or SF Code if you want to learn in detail about this error code.

7. Error Code ‘H5/HS’

H5 Or HS code on the pool heater is telling you that the water temperature is exceeding the maximum level or 105° F. Inadequate water flow is the root reason for this error. 

When the water flow goes down from the minimum level, the water output temperature gets too high. Then the heater shuts down and goes into lockout.

But that’s not all. We have figured out some other major reasons for this error. That includes:

  • Clogged water filter
  • Incorrect setting of the thermostat
  • Faulty temperature sensor. 

How To Fix:

Instead of worrying, go on our suggested solutions to cure the error effectively:

i. Adjust The Remote Thermostat

First up, make sure that the thermostat is set below 104 degrees. If not, set the thermostat at this correct point and set the function “Ok”.

hayward thermostat is set below 104 degrees

ii. Adjust The Water Flow

Next, verify that your pool heater has adequate water flow. Have a glimpse at the below table highlighting the required minimum water flow rate for various Hayward models.

Hayward ModelsMinimum GPM
H150FD 20 GPM 
H200FD20 GPM 
H250FD25 GPM
H300FD25 GPM
H350FD30 GPM
H400FD30 GPM

If your heater water flow is not in this range, adjust the water pressure. That’s quite easy. Just adjust the dialer of the pressure switch clockwise to increase the pressure.

iii. Inspect The Water Temperature Sensor

Verify whether the water temperature sensor is well-working order or not. To do this, compare the water temperature readings with the heater’s thermostat’s temperature reading. If required, replace the thermostat.

iv. Clean The Water Flow

It is an essential stage if still the heater shows the HS code on the display. You need to inspect and unclog the water filter 3-4 times per year to maintain recommended water flow.  

Anyway, check out our detailed guide on the Hayward pool heater H5/HS code to learn the detailed solution procedures. 

8. Error Code ‘HF’

A defective gas valve can lead to a flame despite the valve being inactive. That means the heater is sensing the heat when the gas valve is off.  

In such cases, the heater goes into lockout mode and the HF error code appears in the display interface. Here the blower continues to run until the error is fixed.

How To Fix:

Follow the instructions below to eliminate the HF Code from your heater:

  • First off, reset the heater by cycling the power off and on.
  • Then, look at the sight glass to check the flame’s presence. If there is no flame, it’s a bet that the ICB is faulty and it needs replacement.
  • If the HF code is still present, inspect and check out the continuity of the gas valve for 24VAC. If the resistance is out of range, change the bad valve with the new one.

9. Error Code ‘bO’

The error code, ‘bO’ stands for bypass operations. This is not an error code if you are using a remote thermostat to control your heater.

But in case your heater is not controlled through the remote thermostat, this error is a matter of concern and needs attention. 

Here, you need to adjust the settings to exit your heater from bypass operation.

How To Exit “Bypass Operation” mode On Hayward Pool Heater

Here are the needed steps you need to follow to get your heater out of the automation program or bypass mode:

Step 1: First press the MODE key and set the heater into STANDBY mode.

Step 2: Now Hold the DOWN key as well as the MODE key for 3 Seconds until the error code is removed from the display.

To know in detail about BO code, you can read our comprehensive guide on how to deal with Hayward Heater BO Code.

10. Error Code ‘LO’

‘LO’ error code will flash on your Hayward display for temperature limit switch, water pressure, or vent pressure switch fault.

hayward pool heater error code ‘LO’

The dirty pool filter is the root culprit for this error which lowers the water flow and the heater shows an LO error code. 

How To Fix:

To fix the LO code either you can check out the below flow chart or follow our detailed instructions:

hayward pool heater Lo code flow chart

First, you need to clean your pool filter to increase the water flow rate. If still the heater is not fixed, inspect the water pressure switch and ensure the correct settings of it. Also, the water pump should run perfectly.

Same, inspect and replace the vent pressure switch as well. Next, check the wiring connection of the temperature limit switch. Replace the limit switch if it is faulty. 

Getting it hard to fix the error? check out the detailed guide on the Hayward pool heater LO code.

Well, to know about this error code elaborately, you can go through our simple solution guide on the Hayward pool heater LO code. Alternatively, you can watch the video.

11. Error Code ‘IF’

If the error code on the Hayward display signifies the ignition failure of your heater system. Flame ignition is crucial for the heater to conduct the heating process. 

However, due to a faulty gas valve or flame sensor, blockages in gas orifices, and inadequate gas supply, your Hayward Pool heater will show an ‘IF’ error code.

How To Fix:

Follow the instructions below to fix the issue of an ignition failure

  • Check the connections and the wiring of the gas valve. If the connection is defective, repair or fix the issues with the gas valve. 
  • Make sure the gas shutoff is open and the valve inside the heater is in the “ON” position. Also, it should go through the correct continuity of 24V AC. If not, it is sure that the gas valve relay on the control module is faulty and you need to replace it.
  • Now go to examine the flame sensor. Ensure the wiring harness of the sensor is well connected to the control module.  The sensor should be “5″ in size. 
  • Check for any blockage or clog in the gas burner and orifice. Clear the restriction to eliminate the problem.
  • Call your local gas suppliers to ensure proper gas pressure. 
  • Finally, remove the igniter for testing and replace it if required. Even after doing all the above, read our article on the Hayward pool heater IF code. 

12. Error Code ‘AC’

When the blower vacuum switch is closed when it is expected to be opened, the display shows ‘AC’ as a diagnostic error code. 

hayward blower vacuum switch

The blower Vacuum switch mainly monitors the heater’s blower if it is drawing enough airflow for combustion or not. 

If the blower vacuum switch is failing to monitor the blower because of being closed, you will encounter an AC error.  

How To Fix:

To resolve this issue, you have to manage to open the vacuum switch. Here you go:

  • First, remove the wires and tubing from the switch. Now, measure the continuity between the switch’s terminals. If continuity is present, replace the bad switch. 
  • If the blower continues to run while the heater is off, replace the control module. 

13. Error Code ‘AO’

Error Code ‘AO’ on your Hayward display screen is the clear error indication of the open blower vacuum switch when it is expected to be closed.

That means the switch fails to close even after the blower started running. The fact leads to the ignition trial going into lockout. 

There are a few major reasons that should be noted for this issue:

  • Fault vacuum switch wiring or tubing
  • Defective vacuum switch
  • Or a bad blower

How To Fix:

First off, check for any damage or breakages in the vacuum switch tubing or wiring. Make sure all the connections are firmly secured and the terminals are intact. 

wayward vacuum switch tubing or wiring

Next, inspect the wiring for the blower. Fix the loose blower plug fastened to the control module.

Remove the blower plug from the control module and set the heater into the pool or spa mode. Set the temperature to the lower point. 

Then, measure the resistance for 120VAC across pins 1 and 2. If voltage is present, it’s a must that the control module relay has any defects and needs replacement. 

If still the error doesn’t go away, be sure the vacuum switch is defective. Replace the defective switch with the working one. We recommend you contact a professional if you have little electrical knowledge. 

3 Most Common Hayward Pool Heater Troubleshooting

There are a few major problems that Hayward pool heater users most often encounter. Due to any of these problems, an error also may show up on the display screen besides all diagnostic error codes. 

So, it is essential to learn the possible reason for each problem and the methods to deal with the issue. Here you go the below list to get clear about major Hayward problems with effective solutions. 

1. Pool Heater Not Getting Hot Enough

If your Hayward heater isn’t providing enough heater, you might be dealing with any of the below heater problems:

  • Setting thermostat temperature too low
  • Pump blockage
  • Blow out pilot light
  • Bad wiring or bad connections
  • Too low water flow
  • Heater is undersized

Whatever the reason is, first, move for checking the thermostat and set the temperature high if it is set too low. 

Then inspect the pump for any blockages and clean it. Make sure the pilot is lighting in a well-mannered way. 

Next, check and repair all the bad wiring connections. Increase the water flow by adjusting the bypass. Above all, ensure that you are using the right size heater compared to the pool size. 

2. Pool Heater Is Not Igniting

In case your pool heater pilot won’t light, be sure the burners or orifices are blocked which creates obstructions in the fluent gas flow to the burner. 

Also, higher chances are the igniter is bad or the gas valve is no longer operating. Tripped high-limit switch, bad thermostat functions, not enough gas flow, or poor ventilation also lead to this issue.

Here is all how you will deal with this issue:

  • First up, ensure that your thermostat is in good working order. Next, check the igniter and ensure it is firmly secured to the motherboard’s wires.
  • Clean out the burner orifices to let the gas flow properly. Also, ensure there is sufficient gas flow going to your heater. If not, open the valve all the way and increase the flow rate.
  • Inspect and clean out the ventilation of the heater. If the issue is related to a bad switch. Jump wires on the high limit switch and replace the bad pressure switch.

3. Corrosion In The Heat Exchanger

The corrosion of the heat exchanger of a pool heater occurs due to a variety of reasons. Poor pool water chemistry is the major one of them. The alkalinity level may be too high and the pH level low. 

hayward pool heater low pH level 

Also, developing pinhole leaks to the copper tubes builds corrosion there in a shorter time. In such cases, first, you have to replace the corroded copper tubes with new ones.

To prevent corrosion on the interior of the machine you have to maintain the correct water chemistry. Always check and ensure the optimum pH and alkalinity levels of the pool water.


How can you reset your Hayward Pool Heater?

To reset your Hayward pool heater, first, select the ‘MODE’ button from the keypad. Then keep cycling between ‘STANDBY’ and ‘MODE’. Your heater will reset.

Why does my Hayward Pool Heater keep shutting off?

Your Hayward pool heater cycles on and off mainly due to overheating. Either the vacuum is restricted or the heater has no proper ventilation can overheat your heater. Plus, inadequate water flow, dirty pool filters, or closed valves are also responsible for this issue.

What is the life expectancy of a pool heater?

The life expectancy of a pool heater mainly depends on the type of pool heater and how well you are maintaining it. But in general, a pool heater lasts for 10 to 25 years or more.

Wrapping Things Up!

Well! Now you have an ultimate solution guide to Hayward Pool Heater error codes without any hustle. This guide is very much a textbook. Every error code has a unique fixing process. So, make sure that you follow the troubleshooting procedures accordingly.

Lastly, maintain a regular checkup to eliminate errors timely. Share your experience with Hayward Pool heaters in the comments!

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.

22 thoughts on “Hayward Pool Heater Error Codes [Full List + Reasons + Solutions]”

  1. I have hayward H150 but the Error code I am getting is not in the Manual. It is Showing service light and “56” on the screen. None of the buttons are working. I have turned it off and back on but this code still shows up.

    • Hi Tony

      If the error code is “Sb”(that looks like “56”) then replace the keypad. Your problem will be solved.
      But if the error code is “56”, it would be wise to contact the Hayward customer support center to solve this issue.

      Wish you all the best.

    • Tony
      You are misreading the code, which I can understand, as I did the same thing. The code is actually “Sb”, which looks like it could be 56. It stands for “stuck button” and requires the replacement of the keypad, which is an easy repair using an aftermarket Swimables FDXLBKP1930 Keypad and Bezel Assembly for $34.95 available from Amazon.

  2. Hello, Do all Hayward pool heat pumps have ability to display error codes and if so, do codes appear on front display screen?

    • Hi Frank

      To solve the issue, check the flame sensor & clean it when you get it dirty. Plus, you may need to replace the sensor if it is faulty. Also, make sure the burner below the sensor is burning.

      Hopefully, you will get the solution.

      Well, if it doesn’t work, contact the Hayward customer support center.

      Wish you all the best.

    • Hi Frank

      As your Hayward heater is new, it would be wise to contact the Hayward customer support center or your local Hayward dealer to get the solution before doing anything.

      Wish you all the best.

  3. William

    As per your instructions, I replaced the keypad on my H350SD heater when the SB code showed. Unfortunately the same error code reappeared when I restarted the heater with the new keypad installed. Any other thoughts?

  4. I hAny idea on the possible problem.
    ave a hayward 300HD Pool Heater and I live in Veracruz. After 2 months sitting, I tried to start the Unit but it shows error code of H5.

    • Hi William

      Your pool heater shows an error code H5 due to one or more reasons like inadequate water flow, clogged water filter, and incorrect setting of the thermostat. Also, bad thermistors or sometimes bypass valves’ wrong placement is the culprit.

      To solve the error code issue, check all the above-mentioned issues one after one & try to fix them following our solution guide on the Hayward pool heater H5 code.

      Hopefully, you’ll get the solution.

      Best of luck!


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