Carrier Furnace Ignition Issue
Carrier Furnace Won't Ignite in NYC
If your Carrier furnace tries to start but won't stay lit, or shuts down and locks out after repeated attempts, this page covers the two verified fault codes behind that exact symptom — ignition proving failure and ignition lockout.
What We Check First
A Carrier furnace that won't ignite most often traces back to the igniter or flame sensor circuit rather than the gas valve itself.
Code 34 (ignition proving failure) and code 14 (ignition lockout) are the two verified codes tied to this exact symptom on Carrier furnace control boards.
Quick Answer
A Carrier furnace that won't ignite is most often an ignition proving failure (code 34) — the flame sensor didn't detect a flame after the igniter fired — or an ignition lockout (code 14) after repeated failed attempts. Both point to the igniter/flame-sensor circuit as the starting point for diagnosis.
Common Causes
Igniter or flame sensor fault
Code 34 (ignition proving failure) means the flame sensor did not detect a flame after the igniter fired. A weak or dirty igniter, or a fouled flame sensor, is the most common documented cause.
Repeated failed ignition attempts
Code 14 (ignition lockout) means the furnace tried to prove ignition several times, failed each time, and locked out as a safety measure rather than continuing to attempt ignition indefinitely.
Carrier Error Codes For This Issue
Codes below are informational — a code alone doesn't confirm the fix, and resetting power without addressing the underlying fault often just delays the problem.
34
What it means: Verified: ignition proving failure — the flame sensor failed to detect a flame after the igniter fired.
When service is needed: Service is needed when this code appears because the igniter and flame sensor circuit both need to be checked and cleaned or replaced as needed.
14
What it means: Verified: ignition lockout — the furnace failed to prove ignition after repeated attempts and locked out.
When service is needed: Service is needed any time this lockout code shows, since resetting power without addressing the underlying ignition fault (codes 34, or a related gas/pressure issue) usually just repeats the same lockout.
DIY-Safe Checks vs. Call for Service
DIY-Safe
- Resetting the furnace's power at the breaker or switch once, and observing whether the same lockout code returns on the next call for heat.
- Checking that the thermostat is actually calling for heat and has working batteries, to rule out a thermostat-side issue before assuming a furnace fault.
Professional Required
- Inspecting and cleaning or replacing the flame sensor.
- Inspecting the igniter for wear and testing its ability to reach ignition temperature.
- Diagnosing the ignition control board if the igniter and flame sensor both check out.
FAQ
What does Carrier furnace code 34 mean?
It means ignition proving failure — the flame sensor didn't detect a flame after the igniter fired. This is a verified, documented fault on Carrier furnace control boards, not a generic guess.
What does Carrier furnace code 14 mean?
It means ignition lockout — the furnace attempted ignition repeatedly, failed each time, and locked out as a safety measure. It commonly follows a code 34 condition that wasn't resolved.
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A Carrier furnace that won't ignite is most often an ignition proving failure (code 34) — the flame sensor didn't detect a flame after the igniter fired — or an ignition lockout (code 14) after repeated failed attempts. Both point to the igniter/flame-sensor circuit as the starting point for diagnosis.