Girard Tankless Water Heater Error Code E3

Girard Tankless Water Heater Error Code E3

Error code E3 on the Girard Tankless Water Heater indicates that the ECO gets tripped. When the output temperature exceeds 140 degrees during operation, it will trigger the ECO sensor. As a result, the tankless unit will go into the lockout mode and give an E3 code. 

Because of these possible reasons below, the GSWH-2 will show the E3 code on the UCP: 

  • Insufficient water pressure
  • You may set the thermostat to a higher setting
  • Defective ECO
  • Control Board failure
  • Excessive hot conditions

Throughout this article, I will help you diagnose the fault code E3 and how you can remove this error code. So, let’s dive in. 

Read Also: Girard Tankless Water Heater Error Codes

What Is The Code E3 On Girard Hot Water Heater?

Girard Tankless Water Heater error code E3 indicates that the ECO thermostat has opened. It occurs when the water at the outlet exceeds 140°F during normal operation. 

When the E3 code appears on the UCP, the tankless unit will go into the lockout mode immediately, and the burner will go off. Generally, this fault code will pop up if you set the temperature too high, the water pressure is too low, or the ECO is at fault. 

The fault code will remain on the User Control Panel until you address and resolve those issues. And the next chapter will walk you through each troubleshooting step to fix the error code. Till then, keep scrolling. 

How To Fix Girard Tankless Water Heater Error Code E3?

Here is a table summarizing the key information about fixing Girard Tankless Water Heater Error Code E3:

Insufficient water pressureCheck for blockages in the cold water system and clean debris 2. Clean inlet screen and remove mineral deposits
Temperature set too highAdjust temperature setting on UCP to 115°F or lower
Defective ECO sensorBypass ECO sensor to test. If the unit runs smoothly, replace the ECO sensor.
Control board failureJump ECO sensor wires. If code persists, control board likely faulty
Excessive hot conditionsReplace current ECO with higher degree version

The inlet water pressure should be 45 PSI or greater to operate your tankless water heater smoothly. 

If the water pressure is lower than the requirements, the unit will heat the water to an excessive temperature. Consequently, it will trip the ECO sensor and deactivate the unit by throwing an E3 code. 

Generally, the water pressure will be lower if there is a restriction in the cold water system or the inlet screen gets clogged. 

How To Fix:

To resolve this issue, check the cold water system for blockage and clean the debris buildup if required. Next, pay attention to the inlet screen at the cold water system and remove the mineral deposits.  

If you set the thermostat to a higher temperature setting, the outlet water temperature will exceed the safety level. As a result, it will cut off the ECO and turn off the water heater to ensure your safety. 

How To Fix:

Adjust the temperature on the UCP to reset the E3 code. Use the down button to set the temperature to 115 degrees or lower. This temperature setting will be sufficient for you while ensuring superior safety. 

If the ECO sensor gets faulty, it fails to sense the water temperature correctly and sends the wrong information to the control board. As a result, you will see the E3 code on the User Control Panel. 

How To Fix: 

Before replacing the ECO sensor, bypass the ECO sensor. It will help you determine if the ECO is at fault or not. 

Regarding this, remove the front access panel. Then, locate the ECO sensor on the copper pipe. 

ECO sensor location on Girard Tankless Water Heater

Next, pull out the sensor wires and split them together. If the water heater runs smoothly, understand the ECO is at fault. It indicates that you should replace the ECO sensor with a new one to reset the E3 code. 

The Control Board is the brain of your tankless water heater. If it gets defective, your water heater will operate intermittently. The error code E3 will be the output of a bad control board. 

How To Fix:

Jump the ECO sensor. If the error code still persists, understand the Control Board is at fault. However, I recommend you don’t rush to replace the control board because it will eat up around $200 or more from your wallet. 

Apart from trying the mentioned remedies, adjust the ball valve on the cold water inlet. Sometimes, tightening that valve down will help you reset the error code. 

Though it’s not an actual reason for the error code E3, you can’t avoid it if you live in excessively hot conditions. In the summer, you can get very warm water right out of the ground if you reside in Southern states. In this case, I recommend you replace the current ECO with a higher degree one. 


The ECO thermostat has opened, or the ECO gets tripped, which is what the E3 code means on the Girard Tankless Water Heater. It actually occurs when the outlet water temperature is above 140°F. 

To reset this error code, follow these troubleshooting steps: 

  • Adjust the water pressure by tightening the ball valve on the cold water inlet. Ensure that the water pressure is between 45 PSI and 125 PSI. 
  • Set the thermostat to 115 degrees or lower.
  • Replace the ECO sensor if it’s at fault.
  • Replace the control board if it gets defective.
  • Replace the current ECO with a higher degree one if you live in hot conditions. 

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