Furnace Pressure Error: What It Is, How to Diagnose and Fix

Furnace pressure and humidity control valves are important safety features in any natural gas or propane furnace. They’re also the most likely to fail. If your furnace has a pressure sensor failure, you’ll see an error code on your thermostat such as “FPR Error,” “High-Pressure Sensor Error,” or simply “Pressure Error.” To understand what this means and how to troubleshoot it so you can get your furnace working again and keep your home safe from carbon monoxide poisoning, read this article for all the details.

What Does a Furnace Pressure Error Code Mean?

FPR stands for “furnace pressure regulator.” A furnace pressure regulator is a safety device that shuts off the flow of fuel to the burner in your furnace if the pressure in the system gets too high. Many older furnaces have a single-stage regulator. Newer furnaces have a two-stage regulator that has a separate pressure sensor. A furnace pressure error code can mean one of two things. The first is that the system pressure is too high. Most systems are designed to be between 10 and 15 PSI. If the pressure goes above 25 PSI, the system will shut down to prevent a dangerous situation if the pressure release valve doesn’t open. The second possibility is that the sensor readings are invalid. This can mean a wiring issue, a bad sensor, or a clogged filter on the sensor itself. A bad sensor can throw off the readings and cause the system to overreact.

How to Fix a Furnace Pressure Error

If the pressure is too high, first make sure the pressure release valve is open and nothing is blocking it. If it’s still too high, turn off the gas to the furnace and open the manual release valve to relieve the pressure. If it’s an invalid sensor reading, make sure the wiring between the furnace and thermostat is secure. If that doesn’t solve the issue, clean the filter on the sensor (if you can access it) and/or replace the sensor if necessary. If the pressure is too low, there may be an air leak in your system. The first step is to make sure there aren’t any leaks in the gas line itself. If you’re sure that’s not the problem, check all the fittings on your furnace and air handler to make sure everything is tight. If you’re still getting a pressure error code, you might have a bad pressure regulator. In this case, call a technician to replace the part.

What Causes a Furnace Pressure Error?

A furnace pressure error can be caused by several issues, but most of them boil down to clogs or misalignment in the parts of the system where airflow and pressure are measured. If the pressure reading is too low, that could mean there’s an air leak in the system. If the pressure reading is too high, the filter might be clogged. If the reading is way too high, there could be a serious clog in the system. If the sensor reading is too low, that could mean the wiring to the sensor is loose or there’s a short in the wiring itself. It could also indicate that the sensor has gone bad. If the sensor reading is too high, it could be a wiring issue or a bad sensor.

Other Reasons for a Furnace Pressure Error

If your furnace pressure error code isn’t resolved by cleaning the sensor or replacing the sensor, it could be an issue in the sensor itself. If the sensor is damaged or broken, that could cause the error. If the sensor is clogged with dust or lint, it could be reading an incorrect pressure, even if the wiring is fine. If the furnace pressure error isn’t fixed, it could lead to a pressure release failure. A pressure release failure is a very dangerous situation and can cause extreme damage to your furnace. It’s important to fix any pressure error as soon as possible to prevent this. If the furnace pressure error code is being triggered by a faulty thermostat, the thermostat will need to be replaced to resolve the issue.


Furnace pressure errors are common problems that can be easily resolved with some simple troubleshooting. If your furnace has a pressure sensor error, you may need to clean or replace the sensor to fix the issue. If you’re not sure what’s wrong, call a technician to diagnose the problem and make sure your system is operating at peak performance so it’s safe and efficient. And don’t forget to change the filter in your system at least once a year.