E5 🟡 Repair Required

A.O. Smith Error Code E5: Communication Error

⚠️ The water heater has lost communication with one or more of its components and has shut down. You will not have hot water until this is resolved.

How to Fix A.O. Smith Code E5

  1. Step 1: Check the power to the unit. Make sure the water heater is plugged in securely or that the breaker hasn't tripped. Reset the breaker if necessary.
  2. Step 2: If you have a remote controller, try removing and reinserting the batteries. Sometimes a simple reset can restore communication.
  3. Step 3: If the error persists after these steps, contact a qualified HVAC technician to diagnose and repair the communication issue.
Type: digital display

What Does A.O. Smith Error Code E5 Mean?

The E5 error code on your A.O. Smith tankless water heater indicates a communication problem between the main control board and another component, most often the remote controller or the display panel. Think of it like a dropped call – the different parts of the unit can't talk to each other. This communication breakdown prevents the water heater from operating safely and efficiently, so it shuts down. It's important to address this promptly to restore hot water and prevent potential damage to the unit. This error could stem from a loose wire, a faulty communication cable, or a problem with one of the control boards themselves. Sometimes, power fluctuations can also cause this error. Because multiple components could be at fault, diagnosing the root cause requires some electrical testing. It's not something you can easily fix without the right tools and knowledge.

Common Causes of A.O. Smith Code E5

  • Loose or damaged communication wiring between the main control board and the remote controller/display panel.
  • Faulty remote controller or display panel.
  • Defective main control board.
  • Power surge or electrical interference affecting the communication circuit.

Applicable A.O. Smith Models

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Replacement Parts for A.O. Smith HVAC System Code E5

Main Control Board
Remote Controller
Display Panel