Ruud Error Code 16: Outlet Temp Sensor Fault
How to Fix Ruud Code 16
- Step 1: Power cycle the unit by turning off the breaker for 30 seconds, then turn it back on. This may reset a temporary error.
- Step 2: Check the wiring connections on the outside of the unit for any obvious signs of damage or corrosion. Do not open the unit.
- Step 3: If the error persists after power cycling, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Ruud Code 16
- Turn off the furnace power switch, usually located on or near the unit.
- Turn off the circuit breaker for the furnace. Wait 30 seconds.
- Restore power at the breaker and flip the furnace switch back on.
- Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Ruud Error Code 16 Mean?
The 'Outlet Temp Sensor Fault' (Error Code 16) on your Ruud tankless water heater indicates that the control board isn't receiving a valid signal from the temperature sensor located at the outlet of the unit. This sensor is responsible for monitoring the hot water temperature as it leaves the heater. The control board uses this information to modulate the burner and maintain a consistent output temperature. When the control board detects a fault—either a short, open circuit, or an out-of-range reading—it triggers this error and shuts down the unit. This is a safety measure to prevent overheating or delivering water at an unsafe temperature. It's important to address this issue promptly to restore hot water service and ensure the water heater operates safely and efficiently. Because the unit is locked out, you will not have hot water until the issue is resolved.
Common Causes
- Faulty outlet temperature sensor
- Loose or corroded wiring connections to the sensor or control board
- Damaged wiring harness leading to the sensor
- Defective control board
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit displays error code 16 | Measure the resistance of the outlet temperature sensor at the control board connector. Disconnect the sensor before measuring. | Resistance should be within the range specified in the Ruud service manual for the given temperature (typically around 10-20k ohms at room temperature). |
| Sensor resistance is out of range | Inspect the wiring harness and connector for damage or corrosion. | Wiring and connector are in good condition. |
| Wiring and connector are good, but sensor resistance is still out of range | Replace the outlet temperature sensor. | Error code resolves after replacement. |
| Error persists after replacing the sensor | Check the voltage at the control board connector for the sensor. Consult the service manual for the correct voltage. | Correct voltage is present, indicating a possible control board issue. |
Applicable Ruud Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Outlet Temperature Sensor | SP20364 | — | Find Part |
| Control Board | — | — | — |
Related Codes on Same Models
Other codes that affect the same Ruud model families as 16.
| Code | Description | Severity |
|---|---|---|
| 11 | No Ignition | Critical |
| 12 | Flame Failure | Critical |
| 13 | Improper Combustion | Critical |
| 14 | Overheat / Thermal Fuse | Critical |
| 15 | Inlet Temp Sensor Fault | Warning |
| 21 | Air Supply / Operational Switch | Warning |
| 24 | Flow Sensor Malfunction | Warning |
| 29 | Condensate Neutralizer Issue | Warning |
| 31 | Inlet Water Filter | Warning |
| 33 | Fan Motor Fault | Warning |