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What Does “e2” Mean on Air Conditioner?

Male Technician Repairing And Diagnosing Air Conditioners

It’s a hot summer afternoon, and you desperately need the cold breeze of an AC, but when you turn your unit on, it displays ‘E2″.

What does it mean? Can you fix or bypass it? E2 also called zero crossing detection error, is one of the most common AC error codes.

In most AC models, when your thermostat displays an E2 error message, it indicates room temperature sensor failure. You can do a couple of things to troubleshoot this error, or you can contact a technician to fix the issue.

  • E2 is an error code that most air conditioner models display to indicate room temperature sensor failure.
  • The error results when the AC indoor unit PCB is faulty, if there is a loose connection, if there is a short circuit in the thermostat or PCB, or if the temperature sensor is displaced or has accumulated dust.
  • The best way to fix the E2 error is to replace your PCB, ensure adequate power supply to the thermostat, replace the temperature sensors or thermostat, and ensure your air filter and return ducts are always clean. Also, consider resetting the AC.

This article discusses what E2 means on an air conditioner, the possible causes for this error, and what you can do to fix the error.

Meaning of E2 and What Causes It in an AC

As the introduction highlights, E2 is an error displayed on an AC control panel indicating room temperature sensor failure. It is also called the zero crossing detection error since it results from damage to the zero crossing detector of the AC indoor unit. In addition, if the air conditioner’s PCB is faulty, the thermostat will display an E2 error message.

This is because the Printed Circuit Board(PCB) contains the temperature sensors of an AC, which detects if the room has reached the desired temperature indicated on the thermostat. When the PCB is faulty, the temperature sensors can not tell your home’s temperature, so the system displays an error code.

Let’s look deeper at why your AC might display an E2 error code.

1. Short Circuit

A short circuit can occur in the thermostat or PCB due to poor installation, erratic power changes, or damaged wire connections. When there is a short circuit in either of these locations, the temperature sensor can not work, hence an E2 error code.

2. Loose Wiring

The temperature sensors may not function properly if the thermostat is loosely connected to the power source. This can result in an E2 error message.

3. Old or Damaged PCB

When an AC indoor PCB unit outlives its lifespan, the temperature sensors may not be as effective as they were when the unit was new. Therefore, they may be ineffective in communicating the prevailing room temperature to the thermostat.

4. Displaced Sensor

If the sensor gets displaced from its rightful position, it cannot function as it should. This can lead to an E2 error since the thermostat can not tell the accurate temperature in the room.

5. Accumulated Dirt and Dust

When dust and dirt accumulate on the thermostat or the sensor, they affect the sensor’s efficiency in reading the room temperatures. This will result in an E2 error code.

Ways To Fix an E2 Error on Your AC

Technician Examining Air Conditioner With Digital Multimeter

Consider trying the following to resolve the E2 error.

1. Replace the Temperature Sensors or Thermostat

If the thermostat is faulty, consider replacing it or the temperature sensors. This is a complex task that must be done by a skilled technician.

2. Ensure Adequate Power Supply

It is essential to ensure that all the elements of the AC are correctly plugged in and that there is enough power supply. Inspect the cords for damage that could affect the power supply to the system.

3. Repair or Replace Your AC’s PCB

As discussed in the previous section, a faulty PCB is one of the main causes of an E2 error message on an AC. It is essential to have the PCB inspected by a skilled HVAC technician, and if it is damaged, consider repairing it. However, repairing a PCB might involve a complex process, and most technicians will advise you to replace it, especially if it’s old.

4. Reset the AC

Sometimes, restarting your AC might resolve the E2 error. Consider the following steps:

  • Shut the AC off and turn off the power source.
  • Leave the unit for about two minutes to allow it to reset.
  • Turn the power back on after two minutes.
  • Switch on the AC.

5. Clean Your Air Filter and Return Ducts

Keeping your air filter and return ducts clean promotes unrestricted airflow from inside the house to the evaporator coil and back. This reduces the chances of short cycling, which can cause overheating or freezing of the evaporator coil. Overheating or freezing of the evaporator coil can interfere with the temperature sensor in the PCB, thus resulting in an E2 error.



An E2 error code also called zero crossing detection error, is common in most AC units, and indicates temperature sensor failure. We hope this article has given you an idea of what to do the next time you see an E2 message on your AC control panel.

Frequently Asked Questions

Is It Possible To Use an AC With an E2 Error Message?

No. Since the E2 error indicates temperature sensor failure, the thermostat cannot send instructions to the rest of the system until you resolve the issue.

How Can You Resolve the E2 Error?

The best way to fix the E2 error is to replace your PCB, ensure adequate power supply to the thermostat, replace the temperature sensors or thermostat, and clean your air filter and return ducts. Also, consider resetting the AC.

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