Bradford White Water Heater Error Code 33

Error code 33 on a Bradford White water heater indicates a fault with the heat exchanger outgoing temperature sensor. This sensor monitors the temperature of water as it exits the heat exchanger, providing critical feedback to the control board so it can regulate burner operation and protect the system from overheating. When the control board receives a signal from this sensor that falls outside expected parameters, it triggers code 33 and may shut down or limit heater operation to prevent damage.

The fault can stem from several conditions. Wiring damage is one of the first things to inspect: corroded terminals, pinched wires, or loose connections can cause erratic or absent sensor readings. The sensor itself may have drifted out of specification, which can be confirmed by checking its resistance value against the expected range for the current temperature. Scale buildup is another significant factor, particularly in areas with hard water. Mineral deposits can insulate the sensor from the water or pipe surface it monitors, causing inaccurate readings even when the sensor itself is electrically functional.

Diagnostic steps should follow a logical sequence: visually inspect all wiring and connectors associated with the sensor, measure sensor resistance and compare against specifications, inspect the sensor tip for scale accumulation and clean if necessary, and replace the sensor if wiring and scale are ruled out as causes. The sensor is a serviceable component and replacement is typically the final step after all other causes are eliminated.