A.O. Smith Error Code ECO: Emergency Cutoff

Severity
Critical
Type
digital display
Estimated repair cost: $75 — $200 (parts + labor)
Warning: The ECO code indicates a critical safety shutdown. The water heater has detected an over-temperature condition, which could lead to scalding, tank failure, or even a fire. Do not attempt to restart the unit.

How to Fix A.O. Smith Code ECO

  1. Step 1: Immediately stop using hot water to prevent further temperature increase.
  2. Step 2: Carefully check the area around the water heater for any signs of leaks or unusual smells (like burning plastic). If you notice anything, leave the area immediately.
  3. Step 3: Contact a qualified HVAC technician or plumber to inspect the water heater and diagnose the problem. Do not attempt to reset the high limit switch yourself.

How to Reset A.O. Smith Code ECO

  1. Turn off the unit using the power button on the front panel.
  2. Turn off the gas supply valve.
  3. Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
  4. Restore power at the breaker, then open the gas valve.
  5. Turn the unit back on. If the error returns, the underlying issue needs repair.

What does ECO mean?

The A.O. Smith water heater's 'ECO' or Emergency Cutoff code signifies that the high limit switch has tripped. This switch is a crucial safety device designed to shut down the water heater if the water temperature exceeds a pre-set limit, typically around 190-200°F. When this happens, the heater stops working to prevent dangerous conditions like scalding hot water or, in extreme cases, a tank rupture due to excessive pressure and temperature. Ignoring this warning can be very dangerous.

This error is not something to take lightly. It means the system detected a problem that could cause harm. The most common reasons for this are overheating due to a faulty thermostat, a malfunctioning heating element that won't shut off, or a blockage in the tank that prevents proper water circulation. Because this is a safety issue, it's important to get it checked out by a qualified technician.

Affected Models

Replacement Parts

PartOEM NumberEst. Cost
High Limit Switch — —
Heating Element — —
Thermostat — —

Related Codes on Same Models

CodeDescriptionSeverity
E1 Thermistor Failure Warning
E2 Dry Fire Protection Warning
E3 Sensor Fault Warning
E4 High Temperature Cutoff Critical
E5 Communication Error Warning
E06 Flammable Vapor Detection Critical
LOC Controls Locked Warning
UPR Upper Element Fault Warning
LWR Lower Element Fault Warning