Ruud U802VA050317MSA Error Code A113_F: One-hour Lockout: Ignition Failure
What Does Code A113_F Mean?
Code A113_F on the Ruud U802VA indicates a one-hour lockout triggered by ignition failure. The furnace tried to light four times but could not detect a flame, so it has locked out for safety. This is essentially the lockout status for code A011_F — the furnace will automatically retry after the one-hour period expires.
The ignition sequence works like this: the inducer motor starts, the pressure switch closes to confirm draft, the hot surface igniter heats up, the gas valve opens, and the flame sensor looks for flame. If the flame sensor does not detect flame within a few seconds, the gas valve closes. After four failures, the control locks out to prevent continuous gas cycling.
A dirty flame sensor is the most common DIY-fixable cause — even a thin layer of oxidation can prevent the sensor from detecting the flame. A worn-out igniter that no longer gets hot enough to light the gas is another common cause, though igniter replacement is typically a professional repair. Gas supply problems (closed valve, low pressure) can also prevent ignition.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Faulty igniter | Most common | ✗ Call a pro → |
| Dirty flame sensor | Common | ✓ DIY fix → |
How to Fix It: Clean the Flame Sensor
What You'll Need
Steps
- Turn off electrical power at the breaker or power switch AND shut off the gas supply valve Locate the furnace circuit breaker and flip it to OFF, or use the power switch on or near the furnace. Turn the gas shutoff valve to the OFF position (perpendicular to the pipe). If you smell gas at any point, leave the area immediately and call your gas company.
- Open the furnace access panel and locate the flame sensor Remove the furnace's front access panel. The flame sensor is a thin metal rod with a porcelain insulator base, mounted near the burners. On Ruud U802VA models, it is held by a single mounting screw and extends into the burner flame path.
- Remove and clean the flame sensor Disconnect the wire connector from the sensor and remove the mounting screw. Gently rub the metal rod with a Scotch-Brite pad until it is clean and shiny. Do not use steel wool, as it can leave metal fibers on the porcelain insulator. Wipe clean with a cloth.
- Check the igniter while the panel is open Visually inspect the hot surface igniter — it is a small ceramic or silicon nitride element near the burner. Look for visible cracks. If the igniter is cracked or broken, it needs replacement by a professional. Do not touch the igniter surface with bare hands as oils can cause premature failure.
- Verify the gas supply is on Before reassembling, confirm the manual gas shutoff valve near the furnace is in the ON position (handle parallel to the pipe). Also check that any upstream gas valves are open. A closed gas valve is a simple but easily overlooked cause of ignition failure.
- Reinstall the flame sensor and restore power Reattach the flame sensor with the mounting screw and reconnect the wire connector. Replace the access panel. Turn the gas valve to ON and restore electrical power. Cycle the power (off for 30 seconds, then back on) to clear the lockout. Set the thermostat to call for heat and watch for successful ignition.
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace still fails to ignite after cleaning the flame sensor
- The igniter does not glow when the furnace attempts to start
- The igniter is visibly cracked or broken
- You hear the gas valve click but see no flame at the burners
- You smell gas near the furnace (leave immediately and call your gas company first)
- Code A113_F keeps recurring after flame sensor cleaning
Sources
✓ Verified against manufacturer service manual — March 2026