Pentair Heater Error Codes [Full List + Reasons + Solutions]

If you see error codes on your Pentair heater, you should take appropriate action as soon as possible. The 12 Pentair heater error codes indicate crucial Pentair heater issues.

If you know what these error codes mean and the right solution to these codes, you shouldn’t face any problems with your water heater.

And in this article, we will talk about just these. Here you will get to know the 12 Pentair heater error codes that are: E05, E06, R13, R14, AD0, ERR PS, ERR HLS, ERR AFS, ERR IGN, ERR AGS, ERR SFS and E01/126.

pentair heater error codes

By the end, you will be able to deal with all these codes easily. Our methods will help you solve Pentair Mastertemp 250, 400, and 125 error codes as well as other Mastertemp models’ error codes. So stay tuned.

12 Pentair Heater Error Codes, Their Meanings & Solutions

To properly solve Pentair error codes, you have to know the code’s meaning along with the solutions.

Pentair heater error codes meaning and solutions

This is why below we have elaborated on the 12 Pentair heater error codes, their causes, and effective solutions. Take a look. 

1. Error Code E05: Stack Flue Sensor Is Open

The E05 error code appears when the stack flue sensor detects that the exhaust temperature has exceeded 176°C. As a result of this issue, your heater can shut off completely.

pentair pool heater error code E05


To deal with Pentair heater error code E05, you have to ensure certain things. Here they are:

  • Turn off the Pentair heater
  • See if the thermal regulator has gone bad and causing the water to stay in the exchanger
  • Empty the accumulated water from the heat exchanger
  • See if the gas pressure is fine
  • Make sure that the orifice is not blocked

After ensuring all these points, your Pentair heater won’t have the E05 error code any longer.

2. Error Code E06: Stack Flue Sensor Is Shorted

The most common reason why flue sensors are shorted is improper gas flow in the system. It can happen as a result of many issues, such as a broken gas valve.

pentair heater error code E06


In order to fix the error Pentair code E06, you need to:

  • Check the gas pressure flowing in the system
  • Make sure that the gas pressure is within the perfect limit
  • See if water is clogged anywhere inside the system (it can cause overheating)
  • Make sure to use the right fuel 

And this is how you can get rid of Pentair heater error code E06.

3. Error Code R13: Startup Mode

Pentair heater code R13 is not actually an error code per se. Rather it is actually an indication of heater startup.

pentair heater error code R13

When you turn on the device, this code will come up in your Pentair heater display, but it will go away once the device is completely booted up. In other words, you won’t have to do anything when this error code comes up. 

However, when you find you are struggling with the R13 code, then you can read our ultimate guide on how to deal with Pentair heater error code R13.

4. Error Code R14: Revision Mode

Pentair heater code R14 means that the heater is currently in revision mode. The revision mode is a checkup of your device.

pentair heater code R14

When your heating system goes through every setting, the error code R14 appears. This is why it usually comes up right before another error code or error message. 

5. Error Code AD0: Bad Keypad

Generally, AD0 is related to the stack flue sensor. But the stack flue sensor is set with one key on the keypad. 

Pentair heater bad keypad

This is why it can be concluded that the error code AD0 means that there is something wrong with the keypad.


As the main reason behind the Pentair heater error code AD0 is the keypad, you have to replace it. You can do it easily by following these steps,

  • Open up the front panel of your Pentair heater
  • Detach the membrane and wires connected to the heater control pad
  • Remove the heater control pad from its place
  • Take a new Pentair heater control pad
  • Rewire the new control pad in the same manner as the last one
  • Put everything back on after ensuring proper wiring

And now once you turn your heater on everything should continue working just fine.

6. Error Code ERR PS: Water Pressure Switch Is Open

The error code ERR PS means that the water pressure switch is open, and there is a chance of overflowing.

pentair heater error code ERR PS


In the case of the Pentair heater error code ERR PS, you have to ensure that there is no unwanted water flow. You can do this easily by rotating the water pressure switch.

However, if the water is still flowing through the heater, you have to stop it by fixing the water flow pipe. You may need to call a professional for help.

7. Error Code ERR HLS: Hi Temperature Switch Is Open

This problem occurs when the temperature falls below 57°C. It can happen due to extreme weather, faulty water flow, etc. 

pentair heater error code ERR HLS


This situation is actually a bit tricky. To solve it properly, you have to make sure the water that passes through the heat exchanger is more than 57°C.

This way, the temperature switch will get the reading it was looking for. And as a result, the error code will be gone as well.

8. Error Code ERR AFS: Airflow Switch Is Open

In a good Pentair heater, perfect airflow is established in the system within a minute of a startup.

pentair heater error code ERR AFS or airflow switch is open

If the airflow is not adequate within this time, the heater turns off automatically. The error code ERR AFS is shown as a result of this issue.


You have to make sure that the blower is not restricting airflow to solve this error code. In order to do that, you have to:

  • Turn off the heater
  • Open up the blower fan cover
  • Look for any obstructions or dirt clogged there
  • Clear out the fan thoroughly 
  • Make sure that the fan is strongly secured in its place
  • Put everything back in their place

Now once you put the power back on, your Pentair heater shouldn’t show the error code ERR AFS.

9. Error Code ERR IGN: Ignition Control Module

The error code ERR IGN comes up in the Pentair heater when the ignition control module fails to ignite the heater. So basically, in this error code, you won’t get any ignition in your heater.

 pentair heater error code ERR IGN


The solution to this problem is actually very simple and easy. You only have to make sure that the burner is okay. Here’s how:

  • Press the OFF button
  • Open up the heater to reach the burner inside
  • See if anything’s stuck on the burner
  • See if the burner connection is secured with gas and other lines
  • If the burner is damaged, unscrew it from its place and install a new one
  • Put everything back

At this point, there shouldn’t be the error code ERR IGN displayed on your Pentair heater.

10. Error Code ERR AGS: Gas Shutting Off Automatically

The gas flow in your Pentair heater can shut off on its own due to a low flow rate or a faulty pressure switch. When this happens, you get the error code ERR AGS on your heater display.

pentair error code ERR AGS or gas shutting off automatically


There are a few things you can do in the case of Pentair heater error code ERR AGS. Here they are,

  • See if the water flow rate is above the minimum
  • Adjust the water flow rate
  • Make sure that the water temperature is below 60℃
  • Replace the high-limit switch 

If this doesn’t solve the issue, you have to take your heater for servicing to the professionals. 

11. Error Code ERR SFS: High Stack Flue Temperature

The ERR SFS error code occurs when the temperature of the stack flue gets more than 248°C. Such a situation usually occurs due to a faulty thermal regulator or incorrect fuel supply.

pentair heater error code ERR SFS


In this case, you have to deal with certain points. Here they are:

  • Open up the Pentair heater
  • Locate the thermal regulator there
  • See if it’s perfectly placed in its position
  • Handle the heat exchanger coils clogs, soot, or leakage
  • Make sure that the gas pressure is fine

After all these, your Pentair heater shouldn’t show the error code ERR SFS again.

12. Error Code E01/126: Water Temperature Sensor Is Open

Pentair heater error code E01 and error code 126 are basically the same things. Both these error codes deal with the faulty water temperature sensors of the heater.

pentair heater error code E01 and error code 126


You can adapt the following methods to deal with Pentair error codes E01 and 126. 

  • Turn off the device
  • Open the back panel of the device
  • Locate the thermostat wiring
  • If the wiring seems problematic, replace it
  • If the wiring is okay, then replace the thermostat

And this is how you can perfectly fix the error code E01 and error code 126.

Now that you know everything about the 12 Pentair heater error codes, there shouldn’t be any issue bothering you longer.


What does the service system light mean on the Pentair pool heater?

The service system light on your Pentair pool heater means that the water flow to the heater is not enough. 

What does the stack flue sensor do?

The stack flue sensor in the Pentair heater keeps the flue gas output within 500°F.

How do I reset my pool heater?

To reset a pool heater, you have to press and hold the Up & Down buttons on the control panel.

What causes a stack flue sensor to go bad?

The stack flue sensor can go bad due to sooted exchange, low water flows, and a scaled-up exchanger. 

How do you test a stack flue sensor?

Use a multimeter to test the stack flue sensor. Any reading above 3.5 ohms means that the sensor is okay.

Final Verdict

Dealing with all the Pentair heater error codes is easy. You just have to know the proper solution. And in this article, we have shown you just that. Overall, you won’t have any problem with your Pentair heater from now on.

However, if you have any questions, let us know in the comment below.

About William

William is the founder of 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.

24 thoughts on “Pentair Heater Error Codes [Full List + Reasons + Solutions]”

  1. r14 revision mode. Won’t leave this mode and is showing no further error codes. The unit try’s twice to turn on then shuts down.

    • Hi Daniel

      Pentair heater code R14 means that the heater is currently in revision mode. The revision mode is a checkup of your device. When your heating system goes through every setting, the error code R14 appears. This is why it usually comes up right before another error code or error message.

      Wait and see, which error code shows and deal with it.

      Well, your unit may shut off due to lack of sufficient water flow to the unit or gas flow restriction for a dirty burner assembly, faulty vales setting if you have any, problematic bypass valve in the unit, and faulty thermal regulator. Check and make sure which one is the main reason behind your issue then fix it. If you are not comfortable with the whole procedure, take help from a tech.


  2. New pad and mother board installers and when I turn it on the heater does not work but it reads out on membrane is “3 wire controll”. Any idea what is going on?

  3. Hey guys I have pentair mastertemp 250 that I have been keeping running for 13 years and I can tell you that I have been through three button membrane pads three hot surface ignitors replaced the control board once replaced the ICM once and replaced the entire wiring harness once, replaced the Air flow switch (that was before I knew you could simply blow into it to get it to open again). I can tell you that by far the biggest problem with the unit is that critters love to build their little condos inside every part of the unit. Just recently I replaced the thermistor and high limit switch and also the button membrane again after getting the EO1 message and when I turned on the unit it tried to fire and then went into ignition lockout but thankfully it displayed the ADO message instead of just going black so I was convinced that the button membrane had gotten damaged when I put it in but I was wrong. Apon further inspection I noticed that the critters had gotten into the box that holds the ICM AGAIN! There was a wire that had been disconnected by the bastard. It was still good so I just put it back on. It was the L1 wire from the ICM which I’m guessing has something to do with the stack flue sensor because when I rebooted the system it went through its start up process and then I was able to get it to fire.

  4. Our heater just stops heating. We turn it on and everything is fine but then the heating part shuts off. We are still getting water through it. You can hear it shut off. Then to get the heater shut down we have to unplug it. We tried cleaning the thirmomister. Thank you Any suggestions?

  5. Hello
    i have an error ADo and SF1. we replaced the key pad in 2019 which fixed the heater but i am not sure with both of these errors if the key pad is the issue. any suggestions?

  6. When I put power to heater it reads 128 r=9 and then shuts off. I don’t have any lights on the board lite up to indicate problem. Anyone have this problem and how to fix it?

    • Hi Harry

      128 r=9 is not an error code. In fact, it is a software revision code.

      Well, to solve the issue, it would be wise to contact the Pentair customer support center or your local Pentair dealer.

      Wish you all the best.

  7. Hi,
    I’m getting 128 R14 and then it goes to service heater light turning on.
    I had turned off the gas and forgotten. I had tried turning on the heater with gas line being switched off. Could this have led to this issue? Thank you

    • Hi Tonia

      Check the gas pressure, maybe the propane tank is empty. If the gas pressure is ok & tank is full but you are facing this issue, then it would be wise to take help from the Pentair heater customer support center to solve the issue.

      Wish you all the best.

  8. I have a propane heater. Our tank did run out of propane months ago and gave the error E06. We have refilled the propane and it keeps giving the same error. I can turn it on and off two or three times and it will run fine. But I have to do this every time we run the heater, is there a way to hard reset?

    • Hi Stacy
      To get rid of error code E06, check the gas pressure flowing in the system & make sure that the gas pressure is within the perfect limit. Plus, see if water is clogged anywhere inside the system (it can cause overheating) & make sure to use the right fuel.

      Well, you can reset your pool heater through the circuit breaker. Just unplug all devices that are connected to the circuit breaker & then turn the breaker’s switch off & then turn it on. Wait for 5-6 minutes so that it can restore power before you plug everything back.

      Hopefully, your problem will be solved.

      Best of luck.

  9. I have a Pentair 200 Mastertemp heater for my spa. When I check it in the morning, the “Service Heater” light is on. I do not get any error codes (on the display) or diagnostic lights (on the card). The water will be between 84-92 usually. Set point is 100. If I press “off” and wait about 5 seconds, I can then press “on” and it will fire up and start heating again. It will heat to 100 after about 90 to 120 minutes and then shut off as intended. It seems to function normally (on and 0ff) throughout the day, but then at some point during the day the “Service Heater” light will come on and I will have to hit “off” then hit “on” for it to work again. We have replaced several sensors and the thermal regulator but nothing seems to help.

  10. Can I test or get error messages for the Pentair 250 heater without water running through it? At the end of last season we had issues with the heater shutting down so we winterized it (drained the water) and plan to review and restart in the spring. Any recommendations for maintenance prior to turning on the water would be welcomed.

    • Hi Mark

      Before turning on your Pentair pool heater, inspect it thoroughly & make sure all the components are clean. Also, lubricate Your pool heater where needed & adjust it properly.

      Best of luck!


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