Rheem Error Code 13: Rheem Code 13 - Incomplete Combustion
How to Fix Rheem Code 13
- Step 1: Immediately shut off the gas supply to the unit at the shut-off valve.
- Step 2: Open windows and doors to ventilate the area.
- 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
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs 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 Rheem Error Code 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.
Common Causes
- Blocked or restricted venting, preventing proper exhaust of combustion gases.
- Insufficient gas supply pressure to the unit.
- Dirty or malfunctioning flame sensor preventing proper flame detection.
- Air intake blockage restricting fresh air supply for combustion.
- Faulty gas valve not regulating gas flow correctly.
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Venting appears obstructed | Visually inspect the vent for blockage (leaves, debris, bird nests). | Clear and unobstructed vent path. |
| Gas pressure suspected to be low | Measure the incoming gas pressure at the unit's gas valve with a manometer. | Pressure within the range specified on the unit's nameplate (typically 5-10" WC for natural gas). |
| Flame sensor is suspect | Measure the flame sensor microamp signal while the burner is firing. | Typically 2-10 uA DC, consult Rheem service literature for exact spec. |
| Combustion air intake is suspect | Inspect the combustion air intake for any obstructions. | Clear and unobstructed air intake. |
Applicable Rheem Models
- NCB(gas)
- NPE(electric)
- R801T(gas)
- R92E(electric)
- R92V(gas)
- RGE(gas)
- RH2T(electric)
- RNC(dual_fuel)
- RNE(electric)
- RNG(gas)
- RP16(electric)
- RPB(gas)
- RTGH(gas)
- Rheem Classic(gas)
- Rheem Classic 80 Plus(gas)
- Rheem Classic 80% Gas Furnace(gas)
- Rheem Classic 90 Plus(gas)
- Rheem Classic Plus Series(gas)
- Rheem Classic Series(dual_fuel)
- Rheem Prestige(gas)
- Rheem Prestige 95% Gas Furnace(gas)
- Rheem Prestige Series(gas)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Flame Sensor | SP20741 | — | Find Part |
| Gas Valve | — | — | — |
| Venting | — | — | — |
Related Codes on Same Models
Other codes that affect the same Rheem model families as 13.
| Code | Description | Severity |
|---|---|---|
| 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 |