Bosch Furnace Error Codes: Troubleshooting & Fixes for Common Issues

bosch furnace error codes canada

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If you own a Bosch furnace, you already know it’s built for reliability and energy efficiency. But let’s be real — no HVAC system is perfect, and sometimes things go wrong. When your furnace flashes an error code, it can feel frustrating. What does it mean? Can you fix it yourself, or is it time to call a pro?

Don’t worry — we’ve got you covered. In this Bosch furnace troubleshooting guide, we’ll break down Bosch furnace error codes, what they mean, and how to fix them so you can get your home back to being warm and cozy.

About Bosch and Its Furnaces

Bosch is a name that carries serious weight when it comes to home appliances. German engineering, top-tier efficiency, and long-lasting performance make Bosch a go-to brand for HVAC systems. Their gas furnaces, especially models like the BGH96 and BGH80, are designed to handle the toughest winters while keeping energy bills in check.

These furnaces come packed with smart tech, like two-stage heating and adaptive control systems that optimize performance. But, like any complex system, they can occasionally run into issues. That’s where Bosch furnace diagnostic codes come in handy — they help you diagnose problems before they become major headaches.

How Your Bosch Furnace Communicates Errors

Your Bosch furnace has a built-in self-diagnosis system, which makes Bosch furnace troubleshooting easier. Errors appear in two ways:

  • Digital Error Codes – If your furnace has a display, it will show letter-number combinations (like E5, A31).
  • Blinking LED Lights – On older models, the number of blinks corresponds to a specific issue.

Some errors are simple and can be reset by turning the furnace off and on again. Others signal more serious issues that require expert attention.

Complete List of Bosch Furnace Error Codes in Canada

As we just explained, furnace codes are designed to help identify and resolve issues quickly. By diagnosing the problem early, you can prevent minor glitches from turning into major repairs. Below is a comprehensive list of common error codes, their meanings, and how to fix them.

Error E5/E6 – Fan Malfunction

What It Means: Your Bosch furnace is having trouble with its blower fan.

Possible Causes:

  • Loose or damaged wiring
  • The fan isn’t turning on properly
  • The control board isn’t sending power to the fan

How to Fix It:

  • Check the wiring and make sure all connections are secure.
  • Restart the furnace to see if the issue clears up.
  • If the fan still doesn’t work, it may need to be replaced, or the control board might need repairs.

Error E7 – EEPROM Memory Error

What It Means: There’s a problem with the control board’s memory.

Possible Causes:

  • A software glitch or corrupted firmware
  • A damaged EEPROM chip

How to Fix It:

  • Try rebooting the furnace by turning it off for a few minutes.
  • If the error persists, the control board may need to be reprogrammed or replaced.

Error A31 – Thermostat Connection Issue

What It Means: Your furnace isn’t getting a signal from the thermostat.

Possible Causes:

  • Loose or disconnected thermostat wiring
  • A faulty thermostat

How to Fix It:

  • Check and secure all thermostat wiring connections.
  • If you have a battery-powered thermostat, replace the batteries.
  • Try swapping in another thermostat to see if the issue resolves.

If the Error A31 persists and you’re unable to resolve it, don’t hesitate to reach out to HVAC Service Solutions via the link below. We specialize in diagnosing and fixing thermostat connection issues and other furnace problems, ensuring your Bosch furnace runs smoothly again. 

https://thehvacservice.ca/repair-furnace/

Error: 7 Blinks – Ignition Failure

What It Means: The Bosch furnace failed to ignite the burners.

Possible Causes:

  • Clogged burners or low gas pressure
  • A faulty flame sensor

How to Fix It:

  • Clean the burners and check the gas supply.
  • Remove the flame sensor and gently clean it with fine sandpaper.
  • If the problem continues, you may need professional servicing.

Error: 3 Blinks – Pressure Switch Failure

What It Means: If your Bosch furnace is showing a pressure switch failure code, it means that your unit isn’t detecting proper airflow.

Possible Causes:

  • Blocked venting or intake pipes
  • A malfunctioning pressure switch

How to Fix It:

  • Check for blockages in the vent pipes and clear any debris.
  • Inspect the pressure switch tubing for damage or leaks.
  • If the switch itself is bad, replacing it should solve the problem.
Error Code
Issue Description
How to Fix It
E5/E6
Fan malfunction
Check wiring, restart, replace fan if needed
E7
Memory error in control board
Restart furnace, replace control board if necessary
A31
Thermostat connection issue
Check wiring, replace thermostat if needed
7 Blinks
Ignition failure
Clean burners, check gas supply, clean flame sensor
3 Blinks
Pressure switch failure
Clear venting, inspect pressure switch

Preventative Maintenance to Avoid Bosch Furnace Issues

Nobody wants to deal with a furnace shutting down in the middle of winter. The best way to avoid seeing Bosch furnace error codes is to stay on top of regular furnace maintenance. Here are some key steps:

  • Replace your furnace filter regularly. A clogged filter restricts airflow, making your furnace work harder and potentially causing pressure switch errors.
  • Inspect the venting system. Make sure there’s no debris blocking your furnace’s intake and exhaust pipes.
  • Check the thermostat. Ensure it’s properly wired, has fresh batteries (if applicable), and is communicating correctly with the furnace.
  • Schedule annual tune-ups. A professional technician can catch small issues before they turn into costly repairs.
  • Listen for unusual noises. Grinding, banging, or rattling sounds could indicate problems with the blower motor, burners, or fan.

By keeping up with these simple maintenance tasks, you can significantly reduce the chances of running into Bosch furnace issues and keep your home warm all season long.

What If the Bosch Error Won’t Go Away?

Tried all the fixes and still seeing the same error? That’s your sign to call in a pro. Some issues — like control board failures or major mechanical problems — need expert attention. Ignoring them could lead to bigger (and more expensive) repairs down the line.

Conclusion

If you’ve gone through the troubleshooting steps and your Bosch furnace is still not working, it’s time to bring in an expert. Some furnace problems, such as gas valve failures or electrical control board malfunctions, require specialized tools and expertise. A licensed furnace repair service like HVAC Service Solutions can diagnose the issue and ensure your furnace is running safely and efficiently.

Bosch Furnace Error Codes FAQs

The E5/E6 error code typically indicates a fan malfunction in your Bosch furnace. This can occur if there is loose or damaged wiring, or if the fan itself is not functioning properly. A possible cause could be a problem with the control board not sending power to the fan. To resolve this, check for any loose wiring or connections and reset the furnace by turning it off and back on. If the issue persists, the fan might need to be replaced, or the control board may require repair or replacement. It’s always a good idea to call in a technician if you’re unsure how to proceed.

Error Code E7 refers to an EEPROM (Electrically Erasable Programmable Read-Only Memory) memory error in the control board. This could be due to a software glitch or a damaged EEPROM chip. To fix this, try rebooting the furnace by turning it off for a few minutes to see if that clears the error. If the issue persists, you may need to have the control board reprogrammed or replaced. 

Error Code A31 indicates a thermostat connection issue, meaning your furnace isn’t receiving a signal from the thermostat. Common causes include loose or disconnected thermostat wiring or a faulty thermostat. To resolve the issue, inspect all the thermostat wiring connections and make sure they are secure. If your thermostat uses batteries, replace them. If the problem continues, try replacing the thermostat to determine if the device itself is faulty. If the issue still isn’t resolved, it might be a deeper wiring or control board issue, requiring professional help.

Error Code 7 Blinks signals an ignition failure. This could be caused by clogged burners, low gas pressure, or a faulty flame sensor. Start by cleaning the burners and checking the gas supply for any issues. Also, inspect the flame sensor and clean it gently with fine sandpaper if necessary. 

Error Code 3 Blinks indicates a pressure switch failure, meaning the furnace isn’t detecting proper airflow. The likely causes are blocked venting or intake pipes or a malfunctioning pressure switch. To fix this, check the vent pipes for any blockages such as debris, snow, or dirt. Additionally, inspect the tubing connected to the pressure switch for any cracks or leaks. If you identify any damage or if the switch itself is faulty, replacing the pressure switch will likely fix the issue. Make sure the system is thoroughly cleared of any obstructions before resetting the furnace.

If your Bosch furnace keeps showing the same error code despite troubleshooting, it usually points to a deeper issue that requires professional diagnosis. Some issues, like faulty control boards or gas valve malfunctions, can’t be resolved through basic fixes. It’s important to avoid resetting the furnace repeatedly without fixing the underlying problem, as doing so could lead to further damage. The best course of action is to contact a licensed technician who can diagnose the problem with the proper tools and expertise to ensure your furnace operates safely.

Error Code E1 on a Bosch furnace is often related to a failure in the furnace’s flame detection system. It could be due to a dirty flame sensor, improper gas pressure, or issues with the ignitor. The first step is to clean the flame sensor using fine sandpaper, as a dirty sensor is a common cause of this error. Check the gas pressure and ensure it is at the proper level. 

If the error code on your Bosch furnace doesn’t match anything in the manual or the list of known Bosch furnace error codes, it’s possible that the issue is more complex or specific to your furnace model. In such cases, it’s advisable to contact Bosch customer support or a professional HVAC technician for help. A technician will be able to access diagnostic tools that provide more detailed error readings and will be able to troubleshoot the issue more effectively, potentially saving you time and money in the long run.

Preventing error codes on your Bosch furnace starts with regular maintenance. This includes replacing the furnace filter regularly to ensure proper airflow, inspecting the venting system for blockages, and checking that the thermostat is functioning properly. If you’re able to, clean the burners and flame sensors annually. Scheduling professional maintenance can help catch small issues before they become major problems. Keeping up with routine care will improve the longevity and efficiency of your furnace, reducing the likelihood of errors.

To reset your Bosch furnace after an error code appears, start by turning the furnace off at the thermostat or using the power switch. Wait for at least 5 minutes to allow the system to completely power down. Then, turn the furnace back on and check the display or LED lights to see if the error code persists. If the error is cleared, the issue may have been a temporary glitch. However, if the error code remains, you may need to perform more advanced troubleshooting or contact a professional technician to resolve the underlying issue.

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