Hayward Heater bo Code [5 Easy Solutions]

Automation system programmed in the heater, inadequate gas pressure, thermocouple issue, heater system has broken baffle, and defective wiring and connectors are responsible for Hayward heater bo code. If you see your Hayward heater displaying the bo code, be sure that any of the above factors are responsible for it.

But which reasons are actually causing it, you need to find out. Thus you require to go through the following discussion to know the details causes of each problem and their solutions. Learn all these details, and undeniably, you will be able to fix this bo code issue by yourself.

What Does BO Mean On Hayward Heater?

The bo code in your Hayward heater means bypass operation. Through the bypass operation, the heater bypasses its internal temperature. After the bypass operation, the remote can control the heater’s set temperature. According to the manual, the Hayward heater error code bo is normal if externally controlled.

Hayward Heater bo Code [5 Easy Solutions]

This troubleshooting guide contains all the details causes that are responsible for creating the Hayward gas pool heater bo code and their solutions. Let’s start the discussion:

Note: You can also read how to fix Hayward pool heater IF code by yourself.

1. Automation System Programmed In The Heater

You will encounter the Hayward gas pool heater bo code when your heater is wired or programmed into the automation system. This implies that the automation system is now controlling your Hayward heater. Depending on your Hayward heater’s model, your heater’s automation system may run on due to the following reasons:

  • Programming the logic jumper
  • Flipping a dip switch


To resolve your Hayward pool heater error codes bo, you must ensure that it is not programmed in the automation system. The easy solutions are:

  • Avoid logic jumper programming
  • Make sure the dip switch is not flipping

How Do You Get Your Heater Out of Automation Program Or Bypass Mode

However, if your Hayward heater is already programmed in the automation system, you have to get your heater out of bypass mode. To get your heater out of the automation system or bypass mode, follow the steps below:

  • Use the “Mode” key to change your heater’s settings.
  • Select the “Standby” Option and put the heater on it
  • Press the remote’s “Down” key and hold it and then press the Mode key and hold it simultaneously
  • For 3 seconds, hold down both the “Down” and “Mode” keys as long as the “bo” code doesn’t remove from your heater’s display.

2. Inadequate Gas Pressure

The Hayward heater operates inefficiently due to the inadequate or low gas pressure. It is one of the main reason for which you experiences the Hayward pool heater error codes. The main factors responsible for it are:

  • Defective pump
  • Faulty pressure gauge (Pressure gauge is reading higher or lower than the normal)
  • Dirty skimmer basket and pump pot
  • On/Off switch malfunction
  • Defective gas valves
  • Unadjusted gas pressure


Inspect your Hayward heater’s gas pressure when the heater displays the bo code. The other fixing ways are:

  • Replace the malfunctioning pressure gauge and faulty pump
  • Make sure the pressure gauges are reading normal gas pressure
  • Properly clean the filthy skimmer basket and pump pot
  • Check your heater on/off switch and replace the faulty switch
  • Replace the malfunctioning gas valves
  • Ensure the gas pressure’s perfect adjustment

3. Thermocouple Issue

The defective thermocouple is another reason for which you see the Hayward heater error code bo on the heater’s display. The causes for which thermocouple goes wrong are:

  • Broken or burned out or kinked thermocouple
  • Over time the thermocouple wears down
  • Thermocouples produce a lower voltage
  • Dirt build-up in thermocouple’s inside


If you see the gas in your Hayward water heater is frequently going out, and it is showing the bo code, then probably it’s the thermocouple’s fault, and you need to replace the faulty one. The other easy solutions are:

  • Replace your Hayward heater’s broken, kinked, worn out, or burned out thermocouple
  • Ensure the thermocouple is producing proper voltage
  • Properly clean the thermocouple’s dirt or debris build-up

4. System Has Broken Baffle

The heater will display the bo code if your Hayward heater system goes through the broken baffle issue. The baffle within the heater directs water from the source to the heat exchanger. And then the water backs out into the system. The broken welds that hold the baffle perfectly in place can cause this error code issue.


You can repair the broken-off welds of the baffle. You can re-weld it. And on the broken baffle both sides properly re-weld it. After re-welding, you will see the baffle after removing the unit. Look down the outlet and inlet tubes and make sure the system baffle is not broken and working perfectly.

5. Faulty Wiring and Connectors

Sometimes your Hayward heater’s defective connectors and wiring cause this issue. Improper positioning of the bypass valves or sensor malfunction cause displaying the bo code on your Hayward heater’s display.


Properly check your Hayward heater’s all connectors and wiring. Also, inspect the bypass valve’s positioning and make sure it is positioned perfectly. Replace the faulty sensor and take your Hayward heater out of bypass mode to operate perfectly.


What does HS mean on a Hayward pool heater?

HS on your Hayward pool heater means too high water output temperature. This code means that the heater’s smooth running is facing an issue due to the faulty sensor. The heater should have enough water flow to prevent the water output temperature from getting high.

How do you troubleshoot a pool heater?

To troubleshoot a pool heater, examine its error codes, power sources, and outdoor temperature settings. Also, inspect the heater’s leaks, pilot light, open vent or exhaust, and rust build-up.

Why is my pool heater not working?

Your pool heater is not working mainly due to the insufficient air supply, inadequate gas pressure, or improper venting. Also, if you fail to turn on the gas or lack fuel in the tank, all these could stop your pool heater from working.

What causes ignition failure on a Hayward pool heater?

The main causes of ignition failure on your Hayward pool heater are inadequate gas supply, heater displaying error code, undetected issues in gas supply, pressure switch malfunction, etc.

How do I unlock my Hayward pool heater?

Hold your Hayward pool heater’s lock button until you see the rapid flashes indicator light. Once you see the maximum temperature-lock setting on the digital display, then release the button. However, 90 degrees Fahrenheit is the general range of temperature lock settings.


Now you know what factors are responsible for displaying the Hayward heater bo code and what the code means. If you see this code on your Hayward heater, optimistically, you will resolve this code issue by yourself. Still, if you are struggling with it and need help, you can comment. We will rapidly give you the solution.

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