Ruud UGRA-07EMAES Error Code Flame LED Slow Blink: Marginal Flame Sense Current
What Does Code Flame LED Slow Blink Mean?
A slow-blinking amber flame sense LED on the Ruud UGRA-07EMAES indicates marginal flame sense current. The flame sensor is detecting the burner flame, but the electrical signal is weaker than normal. This can cause the furnace to shut off intermittently during heating cycles as the signal occasionally drops below the minimum threshold.
The flame sensor works by passing a tiny electrical current through the flame to the sensor rod. Over time, the rod develops oxidation and carbon deposits that insulate it from the flame, reducing the current it can conduct. When the current drops to a marginal level, the amber LED flashes as a warning. If the current drops further, the furnace will shut off because it can no longer confirm the flame is present.
The manufacturer's troubleshooting guide recommends cleaning the flame sensor with a Scotch-Brite pad to remove the buildup and checking the ground wire continuity. If the sensor is clean and the LED still flashes, the control board (IFC) may need to be replaced.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Dirty flame sensor rod | Most common | ✓ DIY fix → |
| Faulty control board (IFC) | Uncommon | ✗ Call a pro → |
How to Fix It: Clean the Flame Sensor
What You'll Need
Steps
- Turn off electrical power at the breaker and shut off the gas supply valve Locate the furnace circuit breaker and flip it to OFF. Turn the gas shutoff valve to the OFF position (handle perpendicular to the pipe). If you smell gas, leave immediately and call your gas company.
- Locate the flame sensor Open the furnace access panel and look near the burner assembly. The flame sensor is a thin metal rod (usually bent at an angle) with a porcelain insulator at its base. It has a single wire connected to it and is mounted with one screw near the burners.
- Remove the flame sensor Disconnect the wire from the flame sensor. Remove the mounting screw and carefully pull the sensor out. Handle it by the porcelain insulator or mounting bracket, not the metal rod.
- Clean the sensor rod Gently rub the metal rod with a Scotch-Brite pad until the surface is clean and shiny. Remove all dark oxidation and carbon buildup. Do not use aggressive abrasives. Do not bend the rod or damage the porcelain insulator.
- Reinstall the flame sensor Place the sensor back in its bracket, secure the mounting screw, and reconnect the wire. Ensure the sensor rod will be positioned in the flame path when the burners ignite.
- Restore power and gas, then test Turn the gas supply valve to ON (handle parallel to the pipe) and flip the circuit breaker to ON. Set your thermostat to call for heat and watch the ignition sequence. Pay attention to the amber flame LED on the control board.
When to Call a Professional
Contact a licensed HVAC technician if:
- The amber flame LED still flashes after thoroughly cleaning the sensor
- The furnace shuts off within seconds of igniting even with a clean sensor
- You notice the flame color is yellow or orange instead of blue
- The ground wire appears damaged or disconnected
- The sensor rod is visibly pitted or corroded beyond what cleaning can restore
✓ Verified against manufacturer service manual — March 2026