A.O. Smith Water Heater Error Code 1

Error code 1 means the upper electronic control display and the lower gas control valve/thermostat have lost communication with each other. The two modules exchange data over a 5-conductor cable, and the upper control triggers this code when that data link is interrupted. The heater will not operate normally until the communication fault is resolved.

No. When error code 1 is active, the heater has detected a failure in the control communication link and will not operate the burner normally. Attempting to bypass or ignore this fault is not recommended, as the control system cannot confirm safe operating conditions without a functioning data link between the two modules.

If only the data cable needs replacement, parts cost is typically in the range of $20 to $60. Replacing the lower gas control valve/thermostat assembly generally runs between $150 and $350 in parts, while a new upper electronic control display typically falls in the $80 to $200 range. Adding labor costs for a qualified technician will increase the total repair cost.

Start by inspecting the 5-conductor data cable that runs between the upper display and the lower gas control valve. Check the full length of the cable for visible damage, and firmly reseat the connectors at both ends. If the error persists after reseating the connectors and the cable shows no damage, one of the two control modules may need to be replaced.

A reset may temporarily clear the displayed code, but if the underlying communication fault is still present, the error will return. The 5-conductor cable connection and both control modules need to be inspected and confirmed functional before a reset will result in normal operation.