Lennox EL296UHV Error Code E 206: Gas Valve Second-Stage Relay Failure
What Does Code E 206 Mean?
The Lennox EL296UHV is a two-stage furnace: it can run at a lower firing rate (first stage) for milder weather and step up to a higher firing rate (second stage) when more heat is needed. The SureLight control switches between these rates through separate gas-valve relays. Error E206 means the relay that commands second stage has failed.
With that relay out, the control can no longer command high fire, so the furnace runs on first stage only for the rest of any active heat demand. You still get heat, and in mild conditions you may not notice much difference. The limitation shows up in deep cold, when first-stage output alone may not maintain the thermostat setpoint because the furnace cannot reach its full capacity.
This is where the two-stage design matters: the whole point of the second stage is the extra output for cold snaps, and E206 removes exactly that reserve. If the relay recovers, the code clears on its own; if the second-stage relay has failed for good, restoring full two-stage operation requires replacing the control.
E206 completes the trio of gas-valve control faults on this board alongside E204 (external gas-valve mis-wiring) and E205 (a shorted gas-valve relay contact). Where E205 is a relay stuck shorted, E206 is a relay that no longer actuates the second stage at all.
What You'll Notice
- The seven-segment display shows E 206
- The furnace still produces heat but only ever runs on low fire
- The home struggles to reach the thermostat setpoint during very cold weather
- Heating cycles run longer than usual because the furnace cannot step up to high fire
- The furnace never advances to second stage even on a large temperature call
How This Is Diagnosed
A technician confirms the furnace is stuck on first stage and checks whether the second-stage relay recovers or remains failed across cycles. They verify the control is actually commanding second stage and that the gas valve is not being reached, isolating the fault to the relay rather than the valve or wiring.
Because the second-stage relay is part of the integrated control, a relay that will not actuate is addressed by replacing the control when full two-stage heating is required. If the fault was momentary and the relay recovers, the code clears without further action.
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 cannot keep up with heating demand during cold weather
- The furnace only ever runs on low fire and will not step up
- E206 keeps returning after the furnace cycles
- You want full two-stage heating capability restored
Frequently Asked Questions
Will my furnace still heat with E206?
Yes, but only on first stage. You will have heat in most conditions; the shortfall appears in very cold weather when first-stage output alone may not hold the setpoint.
Why does E206 matter more in deep cold?
The second stage exists to provide extra output when it is very cold. With the second-stage relay failed, the furnace loses that reserve capacity, so cold snaps are when the limitation becomes noticeable.
Does E206 mean the gas valve is bad?
Not usually. The fault is in the control's second-stage relay, not the valve body. Restoring full two-stage operation typically involves the control rather than the gas valve itself.
✓ Verified against manufacturer service manual — March 2026