Ruud Error Code 16: Outlet Temp Sensor Fault

Severity
Warning
Type
digital display
Estimated repair cost: $100 — $250 (parts + labor)
Warning: Your Ruud tankless water heater has detected a problem with its outlet temperature sensor and has shut down to prevent potential issues. You will have no hot water until this is resolved.

How to Fix Ruud Code 16

  1. 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.
  2. 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.
  3. 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

  1. Turn off the furnace power switch, usually located on or near the unit.
  2. Turn off the circuit breaker for the furnace. Wait 30 seconds.
  3. Restore power at the breaker and flip the furnace switch back on.
  4. Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.

What does 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.

Affected Models

Replacement Parts

PartOEM NumberEst. Cost
Outlet Temperature Sensor SP20364 —
Control Board — —

Related Codes on Same Models

CodeDescriptionSeverity
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