A.O. Smith Water Heater Error Code 701

Error code 701 indicates a computer board fault on your A.O. Smith water heater. The main control board has detected an internal failure or a wiring problem that is preventing normal operation. The unit will not heat water until the fault is diagnosed and resolved. The first step is to power off the unit and inspect all wiring connections at the control board for damage or loose terminals.

No. A 701 fault means the control board is not functioning correctly, and the water heater should not be operated until the fault is cleared. The control board manages safety functions including temperature limiting and ignition control, so operating the unit with a board fault could create unsafe conditions. Turn off power to the unit until the issue is repaired.

If the fault is caused only by loose or damaged wiring, repair costs are typically limited to labor charges, generally in the range of $75 to $150 depending on your area. If the control board itself needs replacement, the combined cost of the part and labor can range from $200 to $500 or more depending on the specific model and local service rates.

A homeowner comfortable with basic electrical safety can perform the initial diagnostic step of powering down the unit and inspecting wire connections for looseness, burns, or cuts. If tightening connections resolves the fault, no parts are needed. However, if the control board itself has failed, replacing it requires working with the unit's electrical system and is best handled by a qualified technician.

A simple power reset may temporarily clear the code if the fault was caused by a transient power event, but the 701 code will return if an underlying wiring problem or board failure is present. A reset alone is not a repair. After restoring power, inspect all board connections and monitor the unit to see if the fault reappears.