A.O. Smith Water Heater Error Code 741

Error code 741 means the water heater has detected a communication failure with the remote temperature controller. The unit is not able to properly exchange data with the remote over the wired connection between the two devices. This is most commonly caused by loose or improperly connected wiring at either the remote or the heater's terminal block.

Error code 741 is a communication fault rather than a combustion or temperature safety issue. However, if the remote controller is used to manage water temperature, losing that control link means you may not be able to adjust settings remotely. You should address the fault promptly to restore full control of the unit, but the error itself does not indicate an immediate safety hazard.

If the fix is simply reseating loose wires, there is no parts cost involved. Replacing a damaged communication cable is typically a low-cost repair, generally in the range of $10 to $40 for the cable depending on length. A replacement remote controller can range from $50 to $150 or more depending on the model. If the control board on the water heater requires replacement, costs can range from $150 to $400 or higher, not including labor.

Start by checking that all wiring connections are fully and properly seated at the remote controller terminals and at the terminal block on the water heater itself. If connections look secure, inspect the entire length of the communication cable for physical damage such as cuts or pinching. If wiring is intact and properly connected, the remote controller unit may need to be replaced. If replacing the remote does not resolve the fault, the water heater's control board should be evaluated.

A reset may temporarily clear the code, but the error will return if the underlying wiring or component issue has not been resolved. The communication fault is detected continuously, so as long as the signal path between the remote and the heater remains broken or unstable, the 741 code will reappear. Fix the root cause before relying on a reset.