Bradford White Water Heater Error Code 33

Error code 33 on a Bradford White water heater means the heat exchanger outgoing temperature sensor is faulty. The control board is receiving a signal from that sensor that is outside the expected range, so it flags the error. The cause can be wiring damage, scale buildup on the sensor, or a failed sensor that needs replacement.

Code 33 indicates the control board cannot trust the heat exchanger outgoing temperature sensor, which is a safety-relevant component. The heater may limit operation or shut down entirely as a precaution. Continuing to use the unit while this sensor is faulted is not recommended, as the system may not be able to properly detect an overheating condition.

A reset may temporarily clear code 33, but the error will return if the underlying problem with the sensor or its wiring has not been resolved. Resetting without addressing the root cause is not a fix. You should complete the full diagnostic sequence, including checking wiring, cleaning the sensor, and testing resistance, before relying on a reset to restore normal operation.

Some causes of code 33 are DIY-friendly. Inspecting wiring connections, re-seating connectors, and cleaning scale from the sensor surface are tasks a knowledgeable homeowner can perform. Checking sensor resistance requires a multimeter and some familiarity with reading electrical components. Replacing the sensor itself is a moderate repair, and if you are uncomfortable working around gas or electrical systems, a qualified technician is the safer choice.

If the fix is cleaning scale from the sensor or re-securing a loose connector, the cost is minimal, mainly your time. If the sensor needs replacement, parts typically run in the range of $20 to $80 depending on the model, plus labor if you hire a technician. A professional service call to diagnose and replace the sensor generally costs between $100 and $300 in total, depending on your location and the technician's rates.