Lennox Furnace Error Codes: Their Meanings and Solutions

Uncover the meanings of Lennox Furnace Error Codes and find reliable solutions. Expert advice on common issues like pressure switch lockouts, flame sensor problems, and more from professional HVAC technicians in Mississauga.

Experiencing challenges with your Lennox furnace? Understanding the language of your furnace's error codes is essential in maintaining its efficiency and longevity. As a leading name in the HVAC industry, Lennox furnaces are known for their reliability, but like any sophisticated machinery, they might encounter issues now and then. The good news is, most Lennox furnaces are equipped with self-diagnostic systems that use error codes to communicate specific problems, making the job of troubleshooting and repair more straightforward for homeowners and Mississauga furnace repair professionals alike.

Deciphering Lennox Furnace Error Codes

Observe the flashing LED sequence, which may repeat in a loop. Watch it carefully, make note of the sequence, and match it up with the corresponding code below.

Don’t turn off the power to the furnace while troubleshooting — unless instructed otherwise. Turning off the power clears the current error code.‍

- LED off:

Means no power to the furnace (check circuit breaker)

- LED on:

Means normal operation

1 Flash

Flame sensed with gas valve off.

Faulty gas valve or control board.

Repair Gas Valve or Control Board can cost in Mississauga from $699 to $1399 + HST, depending on the furnace model. Some models can cost more.

2 Flashes

Closed pressure switch with inducer off.

Faulty pressure switch or control board.

Repair Pressure Switch or Control Board can cost in Mississauga from $279 to $899 +HST

3 Flashes

Open pressure switch with inducer on.

Faulty inducer motor or blocked condensate trap or intake/exhaust.

Repair Blockage, Pressure Switch, or Inducer Motor can cost in Mississauga from $199 to $1199 + HST

4 Flashes

Primary limit switch open.

The primary limit switch is a safety device that shuts off the furnace if it detects that the furnace is overheating. This can happen for several reasons:

Dirty Air Filter, Blocked Vents or Registers, Faulty Blower Motor, Issues with the Limit Switch Itself.

Repair Primary limit switch in Mississauga can cost from $159 to $379 depending on the furnace model.

5 Flashes

Roll out switch open.

Possible faulty inducer motor, blocked exhaust or secondary heat exchanger. Professional diagnostic required $119.95 regular hours (service call and diagnosis fee).

Our technicians will identify the problem and tell you how much it will cost to repair it. Once you know the problem and the cost, you can decide if you want to proceed.

6 Flashes

Pressure switch system lockout.

The pressure switch is a safety device that monitors the negative pressure created by the inducer motor to ensure proper exhaust venting out of the furnace. Here are the key points related to this error:

Blocked Venting, Inducer Motor Problem, Pressure Switch Failure, Condensate Blockages, Hose Issues.

Repair Lennox error code 6 can range in Mississauga from $119,95 to $1399 +HST

7 Flashes

Burners failed to ignite, lockout.

It means that the furnace has attempted to ignite the burners but has been unsuccessful, and as a safety measure, it has gone into a lockout mode. This error can be caused by several issues:

Ignition Failure, Dirty or Faulty Flame Sensor,

Gas Supply Problems, Blocked Burners, Control Board Issues, Flame Sensor.

Professional diagnostic required $119.95 regular hours (service call and diagnosis fee).

8 Flashes

Burners lost flame too many times, lockout.

Reset furnace power and check for a different code before lockout. Likely a faulty flame sensor.

Repair furnace flame sensor in Mississauga can cost from $119,95 to $240.00 + HST.

For more detailed information on resolving flame sensor issues, you can read our blog post Furnace Flame Sensor Problem: Understanding and Resolving Issues‍

At HVAC-Group, we take pride in offering efficient and affordable furnace repair services. Our team of professional HVAC technicians is equipped to handle a wide range of furnace issues, ensuring your home stays warm and safe. We serve the Greater Toronto Area, including Mississauga, Brampton, Vaughan, North York, Etobicoke, Oakville, Milton, and the Peel Region. Contact us today for any furnace-related needs and stay warm this winter!

If you would like to learn more about our furnace repair services, this article will be helpful HVAC-Group furnace repair services in Mississauga‍