P0404: Exhaust Gas Recirculation Circuit Range/Performance

The exhaust gas recirculation system, also known as the EGR system, does a very important job for any gasoline engine-powered vehicle. During the internal combustion process, hazardous nitrogen oxide gases form after the air and fuel mixture are ignited in the engine cylinders. It would be very dangerous if these gases were to reach the outside environment. So, the EGR system prevents the gases from being lost by redirecting them back into the engine cylinders. The gases basically get recycled by another combustion again.

The EGR system communicates information about its status to the engine control unit. Whenever the EGR system has an open or closed valve, the engine control unit receives this information. The timing of the EGR valve position is crucial for the recirculation process to be effective. If the valve position is ever open when it needs to be closed or closed when it needs to be open, then the engine control unit will receive this information. That is when it will produce Trouble Code P0404.

Of course, you’re not going to see this code unless you run a diagnostic scan on your engine control unit. Whenever the EGR valve acts unconventionally, you will experience some noticeable symptoms like the Check Engine light activating, acceleration pinging, stalling, and increased emissions. This should prompt anybody to perform a diagnostic scan to see what is going on. Trouble Code P0404 would signify that your EGR valve is performing in an unusual way.

There are a lot of possible causes for this problem. You may have a lot of carbon accumulation in your EGR valve. Perhaps your EGR valve is not moving smoothly for this reason or another reason. You may also have a bad EGR sensor, bad EGR valve, or bad EGR sensor wiring.

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All these problems are moderately severe, so you can probably still drive okay for a little while. But if you ignore the issue for too long, then it could become a much more severe problem. You may even experience permanent engine damage or the inability to pass emissions tests. Don’t wait for things to get this bad. Have a professional mechanic solve the problem for you.

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