Ruud U802VA050317MSA Error Code A013_F: Flame Lost after Established
What Does Code A013_F Mean?
A013_F is the escalated, active version of the flame-loss condition on the Ruud U802VA's Bluetooth Communicating IFC. After the burner is proven lit, the control continuously reads the rectified flame current from the sensor rod. A single momentary dropout is logged as the transient code T013_F (Flame Lost after Established, transient). A013_F is set once that dropout has happened five times inside a single heat call — the 'A' prefix marks it as an active, persistent fault rather than a one-off.
When the fifth loss occurs, the IFC stops retrying and initiates a one-hour lockout, which it reports as the status code A114_F (One-hour Lockout: Flame Lost). During the lockout the control will not start a new heat cycle. This is the board's way of refusing to keep cycling gas at a burner it cannot reliably confirm is lit — repeated relights on a marginal flame are exactly what the safety logic is designed to stop.
The most common cause a homeowner can address is a flame sensor rod that has enough oxide or scale buildup to hold its microamp reading right at the edge of the detection threshold, so it repeatedly drops out mid-run. Other causes — low gas pressure, a partly blocked or dirty burner, or a physically wavering flame — make the flame itself unstable and are technician territory. A013_F is strictly a mid-run flame-loss fault; it is different from A011_F (Failed Ignition), which fires when flame is never established at all, and from A126_F, the UL-level fault for the gas valve being open with no flame sensed.
What You'll Notice
- The furnace lights and delivers heat for a while, then shuts down and stops heating once the lockout trips
- During a bad cycle you may hear the burners cut out and relight repeatedly before the furnace gives up
- After the fifth flame loss the furnace goes quiet and will not restart for about an hour (the paired A114_F lockout)
- The house may not reach the thermostat setpoint because cycles keep terminating early
- The contractor app shows A013_F as an active fault, often after earlier T013_F transient entries
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Dirty or failing flame sensor | Most common | ✓ DIY fix → |
| Low gas pressure | Common | ✗ Call a pro → |
How This Is Diagnosed
Diagnosis follows the escalation logic. Because a contaminated rod is the most common and cheapest cause, the flame sensor is cleaned first and the furnace watched to see whether the repeated losses stop — this is the homeowner-safe step. If the losses continue with a clean rod, the flame itself is suspected of being weak or unstable.
A technician then measures the steady-state flame current in microamps to see how far it sits above the minimum, inspects the burners for a lazy or wavering flame, and checks gas manifold pressure. Those burner and gas-pressure checks are professional work and are not DIY on this furnace.
How to Fix It: Clean the Flame Sensor
What You'll Need
Steps
- Shut off power and gas before you touch anything Turn off power to the Ruud U802VA at the breaker or the furnace power switch, and shut off the gas supply at the manual shutoff valve on the gas line to the furnace. Confirm the furnace is fully off before opening any panel. If you smell gas, leave immediately and call your gas company.
- Locate and remove the flame sensor Remove the burner-compartment door. The flame sensor is a single metal rod with a white porcelain base, mounted at the end of the burner assembly opposite the igniter, with one wire running to it. Note the wire routing, disconnect the wire, and remove the single retaining screw so you can lift the rod out.
- Clean the sensor rod Gently clean the flame sensor rod with a Scotch-Brite pad until the metal is dull-bright. Ruud's guide lists fine steel wool as the cleaning material, but many HVAC technicians prefer a Scotch-Brite pad because it leaves no abrasive residue on the rod. Do not clean or scratch the white porcelain base, and take care not to bend the rod.
- Reinstall and reconnect Set the rod back in its original position, reinstall the retaining screw, and reconnect the sensor wire exactly as it was routed. Make sure the rod does not touch the burner or any metal bracket. Refit the burner door.
When to Call a Professional
Contact a licensed HVAC technician if:
- A013_F or the A114_F lockout returns after the flame sensor has been cleaned
- The flame sensor rod is visibly pitted or corroded, or the white porcelain base is cracked
- The burner flame looks yellow, lazy, or wavers rather than burning steady blue
- Other gas appliances are also affected, suggesting a gas supply or pressure problem
- The furnace keeps re-locking out even with a clean sensor
Frequently Asked Questions
What is the difference between T013_F, A013_F, and A114_F on my Ruud U802VA?
They are the same flame-loss problem at three stages: T013_F is a single transient dropout, A013_F is the active fault after five losses in one cycle, and A114_F is the one-hour lockout status that A013_F triggers.
Why does my furnace lock out for a whole hour?
After five flame losses in one heat call the control refuses to keep relighting a burner it cannot reliably confirm, so it enforces a one-hour cool-down (reported as A114_F). You can clear it early by cycling power, but the cause still needs to be fixed.
Is A013_F dangerous?
The lockout itself is a safety response working as designed, but repeated flame loss should not be ignored. If cleaning the sensor does not resolve it, have a technician check gas pressure and burner condition, since an unstable flame has other causes.
✓ Verified against manufacturer service manual — March 2026