How To Fix Pentair Pool Heater Error Codes E01 [Solved]

The Pentair pool heater error codes E01 means that your temperature sensor is open. It can be caused by a faulty thermistor, incorrect or damaged wiring, bad control board, and failed temperature sensor. 

Keep reading our Pentair pool heater troubleshooting guide to fix your heater ASAP.

Table Of Contents

Pentair Pool Heater Error Codes E01 [Reasons + Solution]

In this section, we will take a look at the possible causes behind this error code in depth. We will also provide you with simple solutions to address each cause.

1. Faulty Thermistor

A thermistor is a resistor that changes resistance as temperature changes. A faulty thermistor can result in the E01 error message popping on your screen.


To replace a Pentair MasterTemp 400 thermistor, follow the steps below.

Step 1: To get to the thermistor, remove the back panel. Use a screwdriver to take off the three screws on the panel. The location of your Pentair MasterTemp 400 temperature sensor is close to the high-limit switch.

Step 2: Remove all of the thermistor’s electrical connections.

Step 3: Loosen the thermistor with a 7/8″ deep socket and remove it. Replace the old one and turn it to stabilize it. 

Step 4: Using the 7/8″ deep socket, tighten the thermistor. Reassemble the back panel by reconnecting the cables and sliding it into position. The screws should be tightened.

2. Incorrect Or Damaged Wiring

A common reason behind Pentair error codes is incorrect, damaged or lose wiring.   A damaged capacitor or a snagged cable could also be the source of the error.


The wiring in your heater should be examined. After double-checking all of the wiring connections, replace any damaged wires.

Ascertain that all connections are secure. The Pentair MasterTemp 400 wiring diagram below may be of use to you.

3. Bad Control Board

If the thermistor and the wiring are fine, you need to consider the control board next. A bad control board is often behind the Pentair pool heater code e01. It can be why your temperature sensor is stuck open.


Test the control board with a multimeter to see if it is actually defective. You can contact Pentair to get you a new control board. Call customer care for a replacement. 

4. Failed Temperature Sensor

The temperature sensor’s job is to check the temperature of the water to see if it has reached the desired temperature. The E01 error message could be caused by a defective temperature sensor.


The sensor can be tested with a multimeter. It should read 10,000 ohms at 77 degrees Fahrenheit (25 degrees Celsius).

Check the chart for 10k thermistors to learn the temperature vs resistance conversion. If the temperature sensor is broken, it must be replaced. 


Why does my Pentair pool heater keep shutting off?

Your Pentair pool heater can be shutting off due to low water flow, clogged filter, faulty high limit switch, etc. Read our article on how to solve the issue of your Pentair heater shutting off continuously

What does E05 mean on a Pentair pool heater?

The Pentair error code E05 indicates an open stack flue sensor. When the temperature of the stack flue rises above a certain degree, this error message will show up on your heater.

What does a thermal regulator do on a pool heater?

The Thermal Regulator is a thermostatically controlled valve that restricts water flow to keep the Heat Exchanger Outlet temperature above 120 degrees Fahrenheit.

Can you manually light a pool heater?

Yes. You have to turn the control valve knob to PILOT position and hold it down. While the knob is pressed in, simultaneously press ‘click-light’ three-four times to turn on the pilot light.

Why does my pool heater smell like gas?

You probably have a gas leak if you can smell gas on your pool heater. Call your local gas company immediately to check on this. Do not take the situation lightly.


Hopefully, you now can deal with the Pentair pool heater error code E01. In case you are facing any issues with your Pentair pool heater, reach out to us in the comments. We will do our best to help you out. 

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 .

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