American Standard AUD1B080A9H31A Error Code 6 Flashes: 115V AC Power Reversed, Poor Grounding, or System Voltage Too Low

What Does Code 6 Flashes Mean?

A 6-flash code on the White-Rodgers 50A65 Integrated Furnace Control (IFC) means the board has detected a problem with its incoming 115V AC power: the hot and neutral are reversed, the ground is poor or missing, or the supply voltage is too low. This matters because the IFC senses flame by reading a microamp current that relies on correct polarity and a solid ground. With the wiring wrong, the flame-sensing circuit can misread, which is why the board flags the condition rather than trusting it.

The most common cause is reversed hot and neutral conductors at the furnace connection, which typically shows up right after installation, a service call, or electrical work elsewhere in the home. A poor or missing equipment ground is the next most common, and genuinely low line voltage is a less common third cause. Because this same polarity/ground integrity underpins flame detection, a 6-flash condition can appear alongside intermittent flame-sensing behavior even though the two share no other parts.

The furnace may still run at times with this code present, but not reliably, and the correction — swapping conductors, repairing the ground, or addressing supply voltage inside the junction box or panel — is electrical work. On this site that is always routed to a qualified technician or electrician rather than presented as a homeowner task.

What You'll Notice

• The diagnostic LED blinks six times, pauses, and repeats.
• The furnace runs intermittently or unreliably, sometimes heating and sometimes not.
• The code first appeared shortly after the furnace was installed or after electrical work was done in the home.
• Flame-sensing behavior seems erratic even though the flame sensor itself looks clean.

Common Causes

How This Is Diagnosed

A technician confirms the fault with a meter rather than guessing. With power safely managed, they verify hot and neutral are on the correct terminals at the furnace junction box, check for a solid equipment ground and low resistance from chassis to ground, and measure the supply voltage under load to rule out a low-voltage feed. Because reversed polarity is the usual finding, correcting the conductors at the junction box and confirming the ground normally clears the code; a persistent low-voltage reading points further upstream to the branch circuit or panel.

When to Call a Professional

This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:

• The LED shows six flashes, especially soon after installation or recent electrical work in the home.
• The furnace runs only intermittently and you suspect a wiring, grounding, or voltage problem.
• Other appliances on the same circuit also behave oddly, suggesting a shared wiring or voltage fault.

✓ Verified against manufacturer service manual — March 2026