Rheem R96VA0702317MSA Error Code 13: Flame Lost After Established

What Does Code 13 Mean?

Fault code 13 on the Rheem R96VA0702317MSA means the IFC confirmed a flame after a successful ignition trial, but then lost the flame signal while the thermostat was still calling for heat. This can happen at any point after ignition — during the first seconds of the heating cycle or partway through a long heat call. The IFC logs the event and the furnace will make additional ignition attempts to restore heat.

Although a single code 13 is considered a non-critical event, repeated flame losses in sequence follow a more serious path. Each lost flame leads to another ignition attempt. If ignition attempts fail after the flame losses, the furnace can accumulate enough failed trials to trigger a one-hour safety lockout (displayed as alternating codes 10 and 13). During a lockout, all heating is disabled. The furnace will automatically retry after the hour expires, but the underlying cause will not have resolved itself.

The most common cause of intermittent flame loss is a weak or dirty flame sensor that cannot maintain a reliable current reading — which is often preceded by code 12 appearing earlier in the heating season. A partially restricted gas supply, an intermittent gas pressure drop from the utility, a blocked condensate drain causing a pressure switch fault, or a failing draft inducer can all produce the same symptom of a flame that lights and then extinguishes. Call a technician if the furnace reaches lockout, if flame loss occurs every heating cycle, or if the burner flame is visibly yellow, weak, or unsteady during operation.

Common Causes

How to Fix It: Clean the Flame Sensor and Check for Common Flame-Loss Causes

What You'll Need

• 1/4-inch nut driver or hex driver
• Scotch-Brite pad (non-metallic abrasive pad)
• Flashlight

Steps

1. Turn off electrical power AND shut off the gas supply valve Flip the furnace circuit breaker to OFF (or use the power switch on or near the furnace). Turn the manual gas shutoff valve to the OFF position (handle perpendicular to the pipe). If you smell gas at any point, leave the house immediately and call your gas company from outside.
2. Remove the access panel and locate the flame sensor Open the burner compartment door. The flame sensor is a thin metal rod with a porcelain insulator at its base, positioned near the burner assembly so the rod sits in the burner flame path. It has a single wire and is held by one 1/4-inch screw.
3. Remove and inspect the sensor Disconnect the wire connector and remove the mounting screw. Slide the sensor out carefully, holding it by the porcelain insulator or bracket. Inspect the porcelain for cracks or tracking marks. If the insulator is damaged, the sensor must be replaced — do not reinstall a cracked sensor.
4. Clean the sensor rod Gently rub the metal rod with a Scotch-Brite pad until the surface is clean and bright, removing all dark discoloration along the length of the rod. Do not use steel wool or sandpaper. Clean only the metal rod and avoid damaging the porcelain.
5. Reinstall the sensor Return the sensor to its mounting bracket, tighten the screw snugly, and reconnect the wire. Confirm the rod will sit within the burner flame path when the burners fire.
6. Check the air filter A clogged air filter restricts airflow and can cause the heat exchanger to overheat, triggering a high-limit shutoff that looks like flame loss. Check the filter and replace it if it is dirty or blocked.
7. Clear any furnace lockout and test If the furnace is in a one-hour lockout (alternating codes 10 and 13), cycle power off at the breaker for 30 seconds, then restore power and gas. Set the thermostat to call for heat and observe the ignition sequence and burner operation through at least one full heating cycle.

When to Call a Professional

Contact a licensed HVAC technician if:

• The furnace has entered a one-hour lockout (alternating codes 10 and 13) and code 13 recurs after the lockout clears
• Cleaning the flame sensor does not stop the flame from dropping out mid-cycle — the sensor likely needs replacement
• The burner flame is visibly yellow, soft, or rolls out beyond the burner ports, which can indicate a combustion air or gas pressure problem
• You suspect intermittent low gas pressure from the utility or regulator — this requires a technician with a manometer to measure supply and manifold pressure
• The condensate drain is blocked and the furnace is shutting down on a pressure switch fault rather than true flame loss
• Code 13 follows immediately after code 12 events earlier in the season, indicating progressive flame sensor degradation that cleaning alone will not fix

✓ Verified against manufacturer service manual — March 2026