State Tankless E32 Error — What It Means
The E32 error code on a State tankless water heater indicates an outgoing water temperature sensor fault. The control board is not receiving a valid temperature signal from the outlet-side thermistor, the sensor that monitors the temperature of water leaving the unit. This fault prevents the heater from accurately controlling output temperature and will typically shut down the unit or prevent it from firing.
The error is caused by a problem with the sensor itself, its wiring harness, the connector, or heavy scale and mineral buildup on the sensor probe that blocks accurate temperature readings. It is not an ignition or gas-valve problem. The controller expects a specific resistance value from the thermistor that corresponds to water temperature, and when that value is out of range, open, shorted, or erratic, the E32 code is triggered.
Before You Replace Anything
Some technicians replace the control board first, thinking the error is a controller problem. Always measure the sensor resistance and inspect the harness and connector before replacing the board, because a failed or dirty sensor is far more common and much cheaper.
Common Causes
- Scale or mineral buildup on the sensor (~40%) Hard water deposits insulate the thermistor probe and prevent it from reading the true water temperature, causing the controller to see an out-of-range or erratic signal.
- Failed outlet thermistor (~30%) The sensor itself has drifted out of specification, shorted, or gone open-circuit due to age or thermal stress.
- Loose or corroded connector (~15%) The harness plug at the sensor or control board is not fully seated, has corroded pins, or shows signs of moisture intrusion.
- Damaged sensor wiring (~10%) The wire harness has been pinched, cut, or chafed, creating an intermittent or open circuit between the sensor and the board.
- Control board input circuit fault (~5%) After the sensor and wiring are verified good, the board’s input circuit for the thermistor may have failed, though this is a secondary diagnosis.
Quick Diagnosis
Answer these to narrow it down fast.
Is there visible scale or mineral buildup on the outlet thermistor probe?
No: Proceed to measure the sensor resistance and inspect the wiring harness and connector for damage or corrosion.
Does the outlet thermistor connector show any corrosion, moisture, or loose pins?
No: The connector is good. Measure the thermistor resistance and compare it to the manufacturer's specification chart in your model's service manual.
Is the measured resistance of the outlet thermistor within the specified range for the current water temperature?
No: The sensor is out of specification or failed. Replace the outlet thermistor and retest.
Step-by-Step Fix
- Shut down the unit and disconnect power at the circuit breaker or service switch before opening the cabinet or touching any electrical components.
- Locate the outgoing water temperature sensor on the outlet side of the heat exchanger. Consult your model’s service diagram if needed.
- Inspect the sensor connector for corrosion, moisture, bent or loose pins, and proper seating. Disconnect, clean with electrical contact cleaner if necessary, and reconnect firmly.
- Check for scale buildup on the sensor probe. If visible deposits are present, clean the probe with white vinegar or a descaling solution, rinse, and dry thoroughly.
- Measure the thermistor resistance using a multimeter set to ohms. Disconnect the sensor from the harness, measure across the sensor terminals, and compare the reading to the thermistor resistance table in your model’s service manual for the current water temperature.
- Replace the sensor if the resistance is open, shorted, or out of the specified range. Use the correct replacement part for your model and install any new O-rings if the sensor mounts in a wet pocket.
- Restore power and test the unit by running hot water and verifying that the E32 code clears and the display shows a normal outlet temperature reading. If the fault persists after sensor replacement and wiring verification, suspect the control board input circuit and consult a technician or the wiring diagram for further troubleshooting.
Parts Often Needed
| Part | Notes |
|---|---|
| State tankless outlet water temperature sensor / thermistor | Amazon | Verify the exact part number for your model from the rating plate or service manual before ordering. |
| Sensor wiring harness | Amazon | Only needed if the existing harness is damaged, cut, or has failed connectors that cannot be repaired. |
| Sensor O-ring kit | Amazon | Replace the seal if your model uses a thermowell or wet-pocket sensor mount to prevent leaks after reinstallation. |
When to Call a Pro
Call a licensed plumber or gas technician if you are not comfortable working with the unit’s electrical components, if you cannot safely access the outlet thermistor, or if the error persists after you have cleaned the sensor, verified the connector, and measured resistance. A professional has the model-specific service manual, thermistor resistance charts, wiring diagrams, and test equipment needed to isolate whether the fault is in the sensor, harness, or control board input circuit. Because tankless water heaters involve both gas and electrical systems, a qualified technician can also perform a full safety inspection and confirm that the unit is operating correctly after repair.
Rough cost: A pro service call runs about $150–$300.