Ruud U802VA050317MSA Error Code A013_F: Flame Lost after Established (Active)

What Does Code A013_F Mean?

Code A013_F on the Ruud U802VA indicates that the burner flame was lost five or more times during a single heating cycle, triggering a one-hour safety lockout. The 'A' prefix means this is an active (persistent) fault — the flame loss is happening consistently, not just occasionally.

This code is the escalated version of T013_F. Each time the flame drops out, the control retries. After five flame losses in one heat call, the system decides the problem is persistent and locks out for one hour to prevent repeated cycling. The lockout can be cleared by cycling power, but without fixing the cause, the code will return.

A heavily contaminated or failing flame sensor is the most common cause. The sensor may have enough buildup that it can barely detect the flame, causing intermittent readings that the control interprets as flame loss. Low gas pressure or a partially clogged burner can also contribute to an unstable flame that the sensor cannot consistently detect.

Common Causes

How to Fix It: Clean the Flame Sensor

What You'll Need

• Scotch-Brite pad
• 1/4-inch hex-head nut driver or screwdriver
• Flashlight
• Clean cloth or paper towel

Steps

1. 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.
2. 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 near the burners, held by a single mounting screw. It extends into the burner flame path.
3. 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.
4. Inspect the flame sensor for damage Check the porcelain insulator for cracks and the metal rod for pitting or excessive wear. If the rod is severely corroded or the porcelain is cracked, the sensor needs replacement — cleaning alone will not fix a damaged sensor.
5. Reinstall the flame sensor and close the panel Reattach the flame sensor with the mounting screw and reconnect the wire connector. Ensure the rod is properly positioned in the burner flame path. Replace the access panel.
6. Restore gas and power, then test Turn the gas supply valve to ON (parallel to the pipe) 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 monitor the furnace through several complete heating cycles.

When to Call a Professional

Contact a licensed HVAC technician if:

• Code A013_F returns after cleaning the flame sensor
• The flame sensor rod is visibly pitted, corroded, or the porcelain insulator is cracked
• The burner flames appear yellow, uneven, or unstable
• Other gas appliances in your home are also experiencing problems (possible gas supply issue)
• You notice a gas odor near the furnace (leave immediately and call your gas company first)

✓ Verified against manufacturer service manual — March 2026