Rheem Water Heater Error Code 33

Error code 33 on a Rheem water heater indicates a faulty outlet thermistor. This is the sensor that measures the temperature of the hot water leaving the unit and reports it to the control board. When the sensor's signal falls outside the expected range, the control board registers this fault. A qualified technician should diagnose and service the unit.

Error code 33 means the control board cannot reliably confirm outlet water temperature, which could result in inaccurate temperature regulation. Continued use is not recommended until the fault is resolved, as the unit may not properly control heating cycles. Shut down the unit and contact a technician promptly.

Resetting the unit may temporarily clear the error code, but if the underlying thermistor or wiring issue is still present, the fault will return quickly. A reset is not a fix for this error. The thermistor circuit must be properly diagnosed and repaired before the code will clear permanently.

Rheem recommends contacting a dealer or qualified service technician for this error. Diagnosing the fault correctly involves measuring thermistor resistance values and inspecting internal wiring, which requires technical knowledge and proper tools. Attempting repairs without this expertise could cause further damage or create safety risks, particularly on gas models.

Repair costs vary depending on the root cause. A thermistor replacement is generally an inexpensive part, but total costs including labor typically range from around $100 to $300 or more. If the control board requires replacement, costs can be higher, potentially ranging from $200 to $600 depending on the model and service rates in your area.