Lennox E290 Error Code — What It Means
E290 on a Lennox furnace signals an ignitor circuit fault. The control board has detected a failed hot-surface ignitor or a problem in the circuitry that triggers the ignitor. This fault specifically points to an issue with the resistance measurement of the ignitor or an open circuit in the ignitor wiring harness. The furnace cannot ignite gas without a working ignitor, so the system locks out and displays this code to prevent unsafe operation.
Common Causes
- Open or failed hot-surface ignitor The silicon-carbide or silicon-nitride ignitor element has cracked, aged out, or burned open and no longer completes the circuit.
- Ignitor wiring harness or connector fault Damaged wires, corroded pins, or loose connectors between the control board and ignitor create an intermittent or open circuit that triggers the fault.
- Integrated control board failure The ignition control module on the board is not supplying the proper voltage to the ignitor circuit even when the ignitor and harness are good.
- Out-of-spec ignitor resistance The ignitor has not completely failed but its resistance has drifted outside the manufacturer’s specified range, causing the control to reject it.
Step-by-Step Fix
- Shut off all power to the furnace at the breaker and the furnace disconnect switch before opening any panels or touching any components.
- Remove the blower-compartment door and locate the hot-surface ignitor mounted in the burner box (it will be a ceramic rod or flat element near the burners).
- Disconnect the ignitor leads and use a multimeter set to ohms to measure resistance across the ignitor terminals, then compare the reading to the specification table in your unit’s installation and operation manual.
- Replace the ignitor if the meter shows open (infinite resistance) or if the reading falls outside the model-specific range printed in the manual.
- Inspect the ignitor harness and connectors for cracks, corrosion, or loose pins, and repair or replace any damaged wiring between the control board and the ignitor socket.
- Check for proper voltage at the control board test points shown in the Lennox troubleshooting flowchart for your model to distinguish between a harness problem and a control-board fault.
- Restore power and run a test cycle, watching for stable ignition and flame sensing, then confirm that the E290 code clears and does not return after several successful cycles.
Parts Often Needed
| Part | Notes |
|---|---|
| Lennox hot-surface ignitor | Amazon | Match the part number on your existing ignitor or consult your model’s parts list for the correct replacement. |
| Ignitor wiring harness | Amazon | Order the Lennox harness assembly for your model if connectors or wires are damaged beyond field repair. |
| Lennox integrated furnace control board | Amazon | Replace only if voltage tests confirm the board is not energizing the ignitor circuit when it should. |
When to Call a Pro
Call a licensed HVAC technician if you are not comfortable working with line voltage or gas appliances, if the fault returns after you replace the ignitor, or if voltage testing indicates a control-board problem. Integrated control diagnostics require model-specific test points and a clear understanding of the Lennox troubleshooting flowchart. A pro will also verify proper gas pressure, flame sensing, and sequence-of-operation timing to rule out secondary issues that can stress the ignitor circuit.