Kenmore Furnace: Flashing Error Code on Display
Blink codes usually indicate a flame-sensor fault, a pressure-switch trip, or a limit-switch issue. Add a photo of your Kenmore Furnace in the box below: the Triage Profile says what it is, how urgent it is, and who to call.
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In the next five minutes
Safe first steps, before the call. Nothing here needs a tool.
If you smell gas, a carbon monoxide alarm sounds, or anyone feels dizzy or sick: don’t touch any switch or plug, leave and get everyone out, then call 911 or the gas company from outside.
No gas smell? Take a photo of the code or flashing light, if you can see it without opening anything, then switch the furnace off at the thermostat and at its breaker.
Don’t use it again until it’s checked, and keep people away from it.
Everything else about this problem
Is it an emergency?
Is a Kenmore furnace error code an emergency?
Usually not, but it can be — the code is the appliance reporting a fault it detected. Note the code. Because this can be an emergency, leave it off and get it checked; don't reset it or turn it back on. If the code returns with a burning smell, smoke or a leak, leave it off and call a pro.
Symptoms & causes
A flashing error code on your Kenmore furnace display indicates the control board has detected a fault, often preventing the unit from igniting or maintaining heat. This warning signal is crucial for identifying the specific problem, which can range from minor issues to more serious component failures. Common underlying causes include a dirty flame sensor, a clogged air filter restricting airflow, or a malfunctioning igniter failing to light the gas.
Tools & parts
A multimeter (e.g., Fluke 115) is essential for testing electrical continuity and voltage on components like the igniter and flame sensor. You will also need a wire brush (e.g., brass brush) for cleaning the flame sensor and a new Kenmore-compatible air filter (e.g., MERV 8) if yours is obstructed. A basic screwdriver set (e.g., Phillips and flathead) will be necessary for accessing the furnace's internal panels.
Safety first
Always begin by completely shutting off the electrical power to the furnace at the main circuit breaker and turning off the gas supply valve to prevent accidental startup or gas leaks. Wear appropriate personal protective equipment, including work gloves and safety glasses, to protect against sharp edges, potential electrical hazards, and dust. Ensure the furnace has had ample time to cool down before touching any internal components, as the heat exchanger and burner assembly can retain extreme heat.
When to call a pro
A professional technician is required if the furnace's main control board is determined to be faulty, as its replacement and configuration demand specialized testing tools and expertise. Persistent issues like a cracked heat exchanger, which poses a severe carbon monoxide poisoning risk, or a malfunctioning gas valve are critical safety concerns that only a certified HVAC expert should address. If the furnace repeatedly trips the high-limit switch after basic troubleshooting, or if you detect any gas odors, immediately contact a professional for a thorough inspection.
Questions people ask
What does a '33' error code on a Kenmore furnace typically mean?
A '33' error code on many Kenmore furnaces commonly indicates a high-limit switch open, signifying the furnace is overheating. This often points to restricted airflow due to a dirty filter, blocked vents, or a failing blower motor. Addressing airflow issues is usually the first step.
Can I clean the flame sensor myself?
Yes, cleaning the flame sensor is a common DIY maintenance task. Locate the small metal rod within the burner assembly, carefully remove it, and gently clean off any carbon buildup with fine-grit sandpaper or a brass brush before reinstallation. This often resolves intermittent ignition issues.
How often should I replace my Kenmore furnace filter?
For optimal performance and indoor air quality, you should replace your Kenmore furnace filter every 1-3 months, especially if you have pets, allergies, or live in a dusty environment. A dirty filter significantly restricts airflow, leading to reduced efficiency and potential error codes.
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What it is, how urgent, who to call
Add a photo of your Kenmore Furnace in the box at the top. The Triage Profile says what it is, how urgent it is, and who to call.