While error codes may differ from model to model, there are some codes you’ll be more likely to encounter. To determine what your error code could mean, consider the following:

Is your model a mini-split air conditioner or a mini-split heat pump?

Are there additional signs of what malfunctioned? A strange noise coming from an important component, for example.

Here are some of the more common error codes for Lennox mini-splits:

• E1 – Indoor / Outdoor Unit Communication: In general, an E1 error code signifies that communication between the mini-split system’s indoor and outdoor units has been disrupted. It could be facing intermittent connection issues or have failed entirely. When the indoor and outdoor units can’t communicate with one another, it will not be able to adequately balance indoor temperatures.
• E5 – Voltage Protection or Temperature Sensor Error: If you own a mini-split heat pump, an E5 error could stand for a problem with the system’s voltage. A repair technician from Tokay Heating & Air may refer to it as overcurrent protection. Both unusually high or low voltage can produce this error code.
  For mini-split air conditioners, this code may also represent voltage issues. In other cases, it’s pointing you to a circuit problem with the outdoor temperature sensor.
• E6 – Indoor / Outdoor Unit Communication: An E6 error code can also refer to a communication problem between the two units, like an E1 code. It might also be an issue with one of the temperature sensors.
• P4 – Compressor Drive Error / High Temperature: A P4 error code will generally be connected to your mini-splits compressor system, located within the outdoor unit. When the compressor drive is malfunctioning, the most likely cause is excessively high temperatures. A high temperature at the discharge line may also trigger a P4 code.
• P6 – Compressor Switch Open or Drive Board Failure: Your mini-split system will have computer boards that make sure the indoor and outdoor units can communicate with one another. If the drive board is malfunctioning, a P6 error code is common.
  When temperatures exceed safe levels, a safety switch should protect the electrical components of your mini-split system, including any components that manage the outdoor compressor. If this switch is open, the P6 code could appear. You may also find the P6 code if the compressor is struggling with high or low pressure concerns.