Coleman DGAA056BDTA Error Code 2 Flashes: Combustion Air Pressure Switch Closed

What Does Code 2 Flashes Mean?

A 2-flash code on the Coleman DGAA056BDTA's Integrated Ignition Control means the combustion air pressure switch is reading closed at the wrong time. This switch has normally open contacts, and at the beginning of every heat cycle — before the inducer builds any draft — the control checks that those contacts are open. If the board sees them already closed, it stops and reports 2 flashes rather than risk running with a switch that can no longer confirm proper venting.

The pressure switch exists to prove the inducer is moving combustion air before gas is allowed to flow. For that safety check to be meaningful, the switch must start open and only close once the inducer generates negative pressure. A switch whose contacts are welded or stuck closed defeats that logic, so the board treats a stuck-closed switch as a hard fault. The most common cause is the pressure switch itself failing closed; less often it is mis-wiring of the pressure-switch circuit, such as a jumpered or crossed connection.

On this single-stage furnace there is only one combustion air pressure switch, so a 2-flash code always points back to that one device and its wiring. It is the mirror image of the 3-flash code on the same board: 2 flashes is the switch stuck closed at rest, while 3 flashes is the switch failing to close once the inducer runs.

What You'll Notice

• The furnace will not begin a heat cycle even though the thermostat is calling for heat
• The green LED behind the blower-door view port flashes twice, pauses about two seconds, then repeats
• The fault appears right at the start of the cycle, before the burners would normally light
• No burner ignition and no heat, often with little or no inducer run time
• The problem persists across multiple thermostat cycles rather than clearing on its own

Common Causes

How This Is Diagnosed

A technician first verifies the fault is genuine by checking the pressure switch's electrical state with power on but before the inducer runs — the normally open contacts should read open at rest. If they read closed with no draft present, the switch has failed and is replaced. Before condemning the switch, they inspect the wiring harness and terminals for a pinched, jumpered, or crossed connection that could make the circuit look closed to the board.

This fault is distinct from a 3-flash code on the same furnace: 2 flashes means the switch is stuck closed when it should be open at the start of the cycle, while 3 flashes means the switch failed to close after the inducer started. Confirming which state the switch is actually in tells the technician whether they are chasing a stuck switch or a venting/inducer problem.

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 furnace shows 2 flashes and will not start any heat cycle
• The code appears immediately at the beginning of the cycle before the inducer builds draft
• The pressure switch or its wiring has recently been serviced or replaced
• The 2-flash code returns after the switch was replaced (suggesting a wiring or control issue)

✓ Verified against manufacturer service manual — March 2026