A.O. Smith Water Heater Error Code 14

Error code 14 means the temperature sensor thermistor inside the immersion probe has shorted. The control board detected a resistance value from the probe that indicates a short circuit condition rather than a valid temperature reading. As a result, the water heater shuts down because it cannot reliably monitor or control water temperature. Cycling the power off for 10 to 20 seconds and back on is the first step to attempt clearing the fault.

Start by turning power off for 10 to 20 seconds and restoring it to check if the fault clears. If it returns, inspect the wiring harness from the immersion probe to the control board for damage, pinching, or corrosion. Also inspect the connector at the probe for contamination or corroded pins. If the wiring and connectors check out, the immersion probe assembly likely needs replacement.

If the fault clears with a power reset, there is no parts cost. Replacement of the immersion probe assembly typically runs in the range of $30 to $80 for the part, depending on the specific model. If a control board is ultimately needed, parts costs can range from $100 to $250 or more. Adding professional labor for diagnosis and repair generally brings total costs into the $150 to $400 range depending on the root cause.

A power reset of 10 to 20 seconds will clear the fault if it was caused by a temporary electrical disturbance. If the thermistor or its wiring has a physical short, the code will return shortly after the reset. Repeated return of the fault after reset confirms a hardware problem that requires further diagnosis of the probe assembly and wiring.

The water heater shuts down when code 14 appears specifically as a safety measure, since it cannot accurately monitor water temperature with a shorted sensor. Operating without reliable temperature data could allow the water to overheat. The unit should not be forced back into operation if the fault continues to return after a reset.