Quick answer: Lennox code 223 (E223) means the furnace’s low pressure switch failed open, so the control cannot confirm the vent is drafting properly and will not light the burners. In Chicago-area winters the most common causes are a vent or intake pipe blocked by snow or ice, a clogged condensate trap, water in the pressure switch tubing, or a weak inducer motor.
Safety first: if you smell gas, do not reset or relight anything. Leave the home and call Nicor Gas at 1-888-642-6748 or 911 from outside.
What Does Lennox Error Code 223 Mean?
Lennox describes code 223 as low pressure switch failed open. Before lighting, the combustion air inducer starts and pulls air through the furnace and out the vent. The pressure switch closes once it senses enough draft. If it does not close, the control assumes the vent may be blocked and stops the ignition sequence to prevent unsafe venting.
Common Causes of Code 223
- Blocked vent or intake pipes outside, from snow, ice, leaves or animal nests. This is very common on high-efficiency furnaces with PVC pipes after a snowstorm.
- A clogged condensate trap or drain on high-efficiency furnaces such as the EL297V and SLP99V, which backs water up into the inducer area.
- Water, a crack or a kink in the pressure switch tubing.
- A weak or failing combustion air inducer motor.
- A failed pressure switch.
- Improper vent sizing or too many elbows from a previous installation.
Safe Checks You Can Do First
- Check the outside PVC pipes. Clear snow, ice or debris from around the intake and exhaust pipes where they exit the house. Do not push anything into the pipes.
- Look at the condensate drain line. If water is pooling around the furnace or the drain line is clogged, that can trigger code 223.
- Restart the furnace once by turning the furnace switch off for 30 seconds and back on.
Never bypass or jump a pressure switch. It is a safety device that protects your home from carbon monoxide.
What a Technician Will Check
We measure the actual draft pressure with a manometer and compare it to the switch rating, inspect the vent and intake, clean and test the condensate trap and tubing, and check the inducer motor and switch. That pinpoints whether the problem is a blockage, a drainage issue, a worn inducer or a bad switch. As a Lennox Premier Dealer, we use the correct Lennox switch rated for your furnace.
Seeing a Lennox code in the Northwest Suburbs?
Pure Comfort Heating and Cooling is a Lennox Premier Dealer in Streamwood, IL. Diagnostics are $75, or $99 on evenings, weekends and holidays, and you approve a flat-rate price before any repair. Phones are answered 24/7.
Frequently Asked Questions
Why does code 223 happen after a snowstorm?
Snow and ice can cover or plug the PVC intake and exhaust pipes on high-efficiency furnaces. Clearing the area around the pipes often solves it. If the code continues, the problem is likely inside the furnace.
Is code 223 dangerous?
The code itself means the safety system is working: the furnace refuses to light because it cannot confirm safe venting. Do not bypass the switch. Call for service if the code repeats.
What’s the difference between code 223 and code 227?
Code 223 means the low pressure switch never closed when the furnace tried to start. Code 227 means the switch opened during ignition or while the furnace was running. Both point to draft, drainage or inducer problems.
How quickly can you fix code 223?
Emergency calls usually get a technician within one to three hours, and many pressure switch problems are fixed on the first visit.
We service Lennox furnaces from our shop in Streamwood across Streamwood, Bartlett, Hoffman Estates, Schaumburg, Elgin, Hanover Park, Roselle and the rest of the Northwest Suburbs.
Looking up a different code? See our full Lennox furnace error code guide.