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How to Fix Tempstar Furnace Codes Smoothly

A key component of homeownership involves maintaining and troubleshooting household appliances. One such vital appliance is the furnace, especially during cold winter months.  If you own a Tempstar furnace, understanding…

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A key component of homeownership involves maintaining and troubleshooting household appliances. One such vital appliance is the furnace, especially during cold winter months. 

If you own a Tempstar furnace, understanding Tempstar furnace codes can be immensely helpful when you encounter operational issues. Tempstar furnace codes help identify specific problems and guide you towards the appropriate solution.

In this guide, we will explore common Tempstar furnace codes, their meanings, and how to fix them.

Common Tempstar Furnace Codes and Their Meanings

Tempstar furnace codes are a series of flashing lights displayed on the LED screen of your furnace’s control board. The control board is usually located within the furnace cabinet or on the blower compartment door. These codes flash in unique patterns to signal normal operation or system malfunctions.

Interpreting these codes is an integral part of diagnosing issues with your Tempstar furnace and restoring it to its optimal operating condition.

READ: How to Troubleshoot Heil Furnace Codes Quickly

Decoding Tempstar Furnace Codes

Reading Tempstar furnace codes involves counting the number of flashes displayed on the LED screen. Each flash count corresponds to a specific issue. Here’s a table summarizing what each flash count signifies:

Flash CountCode Description
One flashSystem lockout (failed to detect flame)
Two flashesSystem lockout (trial for ignition lockout)
Three flashesPressure switch stuck open
Four flashesOpen high limit device
Five flashesFlame sensed without gas valve
Six flashesPressure switch cycle lockout
Seven flashesSoft lockout (low flame sense signal)
Eight flashesLow flame
Nine flashesCheck polarity

A Deep Dive into Troubleshooting Tempstar Furnace Codes

The Tempstar furnace codes guide you to take the necessary action, depending on the specific issue indicated by the flash count. Here’s how to address each of the furnace codes:

One flash: System lockout (failed to detect flame)

This code implies that the system has failed to detect a flame where one should be. Try resetting the furnace by turning off the power for about a minute before turning it back on. If the problem persists, you might have a faulty flame sensor or gas valve. In this case, professional help is recommended.

Two flashes: System lockout (trial for ignition lockout)

This code indicates that the system is experiencing problems with ignition. It’s advisable to check the pilot light and gas supply. If you can’t resolve the issue, seek professional assistance, as the problem might stem from a more serious mechanical or electrical issue.

Three flashes: Pressure switch stuck open

If you see three flashes, the pressure switch might not be closing as it should. This might be due to a blocked vent pipe, air intake pipe, or a cracked or clogged pressure switch hose. These should be checked and cleared or replaced if necessary.

Four flashes: Open high limit device

This code indicates that your Tempstar furnace is overheating. This can be due to a dirty or clogged air filter, improper duct size, or a faulty blower motor. It’s advisable to clean or replace the air filter and ensure the duct size matches your furnace’s capacity.

Five flashes: Flame sensed without gas valve

This code is a serious safety concern, suggesting that the control board is detecting a flame when there should be none, hinting at a gas valve leakage. This situation calls for immediate professional help.

Six flashes: Pressure switch cycle lockout

This code suggests that there might be an issue with the pressure switch wiring or the pressure switch itself. It might also be a result of a malfunctioning inducer motor. Ensure the wiring is intact and consider replacing the pressure switch if necessary.

Seven flashes: Soft lockout (low flame sense signal)

This might indicate an issue with the flame sensor such as dirt build-up or a faulty sensor. The flame sensor can be cleaned using a non-abrasive cleaner. If the problem persists, consider replacing the flame sensor.

Eight flashes: Low flame

This code might suggest that the burners are dirty or there’s low gas pressure. You may need to clean the burners or adjust the gas pressure. In some cases, a professional might need to evaluate the system.

Nine flashes: Check polarity

This code suggests that the power supply has reversed polarity. Check your electrical wiring against the schematic and if you’re uncertain, consult a certified electrician to prevent the risk of electric shock.

READ: How to Troubleshoot American Standard Furnace Codes


Understanding Tempstar furnace codes can go a long way in maintaining your furnace’s efficiency and longevity. While some issues can be resolved at home, others might require the expertise of a professional. Always adhere to safety measures and turn off the power supply before attempting to fix any issues.

We hope this comprehensive guide has equipped you with the knowledge needed to troubleshoot Tempstar furnace codes effectively.

I'm an HVAC enthusiast and a passionate writer dedicated to sharing valuable insights and practical tips about heating, cooling, ventilation, and air conditioning systems.

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Hi there, I'm Robert Brooks

Hi there, I'm Robert Brooks

I’m so glad you are here! Welcome to my website, where I’ll share easiest HVAC troubleshooting tips, buyers guides, and everything about HVAC cooling and heating system. Learn more about me.

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