Ruud U802VA050317MSA Error Code A113_F: One-hour Lockout: Ignition Failure
What Does Code A113_F Mean?
A113_F is a status code, not a separate failure: it is how the Ruud U802VA's Bluetooth Communicating IFC reports that it has entered a one-hour lockout because of ignition failure. The root event is the same one described by A011_F (Failed Ignition) — the control ran its ignition sequence (inducer proves draft, hot-surface igniter glows, gas valve opens, flame sensor looks for a rectified flame signal) four times and never confirmed flame. After the fourth trial, instead of continuing to cycle gas, the IFC stops and shows A113_F to indicate the lockout is active.
What you actually experience during an A113_F lockout is a furnace that has gone quiet and will not respond to the thermostat: no inducer, no igniter, no heat, for up to one hour. This is deliberate. The lockout gives the system time to settle and prevents the control from repeatedly opening the gas valve at a burner it cannot prove is lit. When the hour elapses, the control automatically releases the lockout and runs the ignition sequence again. If the underlying problem is still there, it will fail four more times and drop straight back into A113_F — which is why the lockout can appear to repeat on a roughly hourly rhythm until the cause is fixed.
The key point for a homeowner is that clearing A113_F is not the same as fixing it. Cycling power off and on ends the lockout early, but if the flame sensor is still contaminated (the most common DIY-fixable cause), or the igniter is weak, or gas is not reaching the burner, the next attempt just re-locks out. Cleaning the flame sensor addresses the most common root cause and is what actually prevents re-lockout. Note this is the ignition-failure lockout; the parallel lockout for losing flame after it was established is A114_F, driven by the A013_F flame-loss condition.
What You'll Notice
- The furnace is completely idle and unresponsive to the thermostat for about an hour — no inducer, no igniter, no heat
- The contractor app shows A113_F as the active lockout status
- Roughly once an hour you may hear the furnace attempt to start, fail, and go quiet again
- The house temperature drifts below the setpoint while the lockout is active
- You may have seen A011_F logged just before the lockout began
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Faulty igniter | Most common | ✗ Call a pro → |
| Dirty flame sensor | Common | ✓ DIY fix → |
How This Is Diagnosed
Because A113_F and A011_F share the same root cause, diagnosis is the same: work the ignition sequence in order. The flame sensor is cleaned first, since an oxidized rod that fails to prove a briefly-lit flame is the most common and cheapest cause a homeowner can address. If the burners visibly never light, attention moves to whether the igniter is glowing and reaching temperature, and whether gas is actually reaching the valve (manual shutoff open, LP tank not empty).
A technician confirms by reading flame current in microamps on a lit burner, checking igniter resistance, and measuring gas manifold pressure — all of which involve the live gas valve and burner and are not DIY. The goal is to fix the cause so the automatic retry after the hour succeeds instead of re-locking out.
How to Fix It: Clean the Flame Sensor to Prevent Re-Lockout
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:
- The furnace re-enters the A113_F lockout after the flame sensor has been cleaned
- The burners never light at all during the retry, pointing to the igniter or gas supply
- The igniter does not glow, or glows only dimly, when the furnace attempts to start
- The lockout keeps repeating on an hourly rhythm despite your attempts to clear it
- Nearby gas appliances are also starved, suggesting a gas supply or pressure problem
Frequently Asked Questions
Is A113_F the same problem as A011_F?
Yes. A011_F is the ignition-failure fault after four failed trials, and A113_F is the one-hour lockout status the control shows once that failure trips. Fix the cause of A011_F and A113_F stops recurring.
Do I have to wait a full hour for the furnace to work again?
No — cycling power off and back on clears the lockout right away. But if the underlying cause is not fixed, the furnace will just fail its next ignition attempt and return to A113_F, so resetting alone is not a repair.
Why does the furnace keep locking out at about the same interval?
When the hour elapses the control automatically retries. If the flame sensor, igniter, or gas supply issue is still present, it fails again and re-locks out, producing the roughly hourly pattern until the root cause is resolved.
✓ Verified against manufacturer service manual — March 2026