Rheem Error Code 13: Rheem Code 13 - Incomplete Combustion

Severity
Critical
Type
digital display
Estimated repair cost: $75 — $200 (parts + labor)
Warning: A Rheem Code 13 indicates incomplete combustion, which can produce dangerous carbon monoxide. Shut down the unit immediately and call for professional service.

How to Fix Rheem Code 13

  1. Step 1: Immediately shut off the gas supply to the unit at the shut-off valve.
  2. Step 2: Open windows and doors to ventilate the area.
  3. Step 3: Evacuate the premises and contact your local gas company or a qualified HVAC technician for inspection and repair.

How to Reset Rheem Code 13

  1. Turn off the unit using the power button on the front panel.
  2. Turn off the gas supply valve.
  3. Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
  4. Restore power at the breaker, then open the gas valve.
  5. Turn the unit back on. If the error returns, the underlying issue needs repair.

What does 13 mean?

Rheem tankless water heaters and furnaces are designed with safety in mind. When the system detects incomplete combustion, meaning the fuel isn't burning completely, it shuts down and displays error code 13. This is a critical safety feature because incomplete combustion can release carbon monoxide (CO), a colorless, odorless, and potentially deadly gas.

This error can stem from various issues affecting the air-fuel mixture or the venting system. It's important to address this issue promptly to ensure your safety and the proper operation of your Rheem unit. Because CO is so dangerous, troubleshooting should be left to qualified technicians.

Affected Models

Replacement Parts

PartOEM NumberEst. Cost
Flame Sensor SP20741
Gas Valve
Venting

Related Codes on Same Models

CodeDescriptionSeverity
A001 Ignition Failure Warning
A003 Abnormal Ignition Warning
A004 False Flame Detection Warning
A008 Exhaust Temperature High Warning
A011 No Flame Detected Warning
A021 Over-Temperature Warning
A031 Inlet Thermistor Open/Short Warning
A041 Outlet Thermistor Open/Short Warning
A043 Water Level Error Warning
A051 Fan Motor Abnormality Warning