Furnace igniter glows but the burners never light

By Jason Dearmin · Last reviewed November 14, 2026 · How we check facts

Why a glowing igniter is not the whole story

A hot surface igniter only starts the sequence. Carrier's status code 34 (ignition proving failure) lists these causes: oxide buildup on the flame sensor, low flame-sense microamps, a manual gas valve that is shut off, control ground continuity problems, a defective gas valve or gas valve turned off, low inlet gas pressure, inadequate flame carryover or rough ignition, a defective hot surface igniter and a grounded flame sensor.

Carrier's consumer page lists "no heat despite the igniter glowing" among the symptoms of a bad flame sensor, with the note that a flame sensor is only one possible cause because ignition, wiring, grounding, gas supply, combustion or control problems can look the same.

Safe things to check yourself

1. Confirm the gas shutoff valve on the pipe near the furnace is open (handle in line with the pipe).
2. Check whether other gas appliances (stove, water heater) are working. If none work, call your gas utility.
3. If you use propane, check the tank gauge.
4. Look at the control board LED and note the code.
5. Make sure the furnace power switch is on and the blower door is fully seated.

What needs a technician

• Measuring flame-sense microamps (Carrier lists 0.5 microamps DC as the minimum, with 4.0 to 6.0 nominal, for its control)
• Cleaning or replacing the flame sensor
• Testing the gas valve, inlet gas pressure and ground continuity
• Replacing the hot surface igniter or checking flame carryover

After repeated failed attempts the control locks out. Carrier says ignition lockout (code 14) auto-resets after three hours; Goodman says its control locks out after three failed ignition attempts and resets after one hour or by interrupting power. Do not keep resetting; a lockout that returns needs service.

Safe checks when a furnace igniter glows but no flame appears

1. Check the gas valve handleMake sure it is open and in line with the pipe.
2. Check other gas appliancesIf they also do not work, the issue is the gas supply; call your utility.
3. Check propane levelRefill if low.
4. Note the LED codeLook it up for your brand and record it for the technician.
5. Call a technicianFlame sensor, igniter and gas valve work is for a licensed professional.

Frequently asked questions

Does a glowing igniter mean the igniter is good?

Not necessarily. It may glow but be weak, and the problem might be gas, ground continuity or the flame sensor. A technician can measure to tell.

How many ignition attempts does a furnace make?

It depends on the control. Carrier's code 34 entry says the control tries three more times after the first failure, and Goodman describes lockout after three attempts. Carrier's own consumer page says the number varies by model.

Sources

• SP05-59 Service and Maintenance Procedures: Deluxe 4-Way Multipoise 2-Stage Direct-Vent Condensing Gas Furnace (Carrier (shareddocs.com)) Covers: Carrier 2-stage condensing gas furnaces with the status-code LED control described in the document. Other Carrier, Bryant and Payne boards can use different codes; check the service label on your furnace.
• Furnace Flame Sensor: What It Is, Why It Fails, and How to Fix It (Carrier)
• RS6612023 Service and Troubleshooting: 34.5" Chassis ACVC96/AMVC96/GCVC96/GMVC96 Gas Furnaces (Goodman Manufacturing (Daikin)) Covers: Goodman and Amana 96% two-stage condensing furnaces in the 34.5" chassis.

Safety note: this page is general information drawn from the sources above. Gas, combustion and line-voltage repairs belong to a licensed professional. Your own equipment's label and manual take priority over anything here. Read the full disclaimer.