OBD-II Trouble Codes

P0406 Code: Exhaust Gas Recirculation Sensor A Circuit High

Reading Time: 3 minutes

Trouble codes are designed to provide a starting point for diagnosing problems in a vehicle. Without them, it would be more difficult to figure out what’s wrong with your car. Each code has a unique combination of letters and numbers.

If you want to fix your car after seeing code P0406 on your code reader or scanner, read this article to know what it means, its causes, and symptoms.

What Does the P0406 Code Mean?

Diagnostic trouble code (DTC) P0406 stands for “Exhaust Gas Recirculation Sensor A Circuit High.” It means that the powertrain control module (PCM) perceives a high voltage signal from the exhaust gas recirculation (EGR) position sensor.

egr valve position sensor
Code P0406 means that your car computer perceives a high voltage signal from the EGR position sensor.

As its name implies, the EGR position sensor detects the position of the EGR valve. The PCM uses the sensor signal to monitor and adjust EGR valve operation.

Code P0406 may get registered when the signal being sent back by the EGR position sensor to the PCM is higher than the specified range. The check engine light will activate as the PCM sets this code.

Note: The definition of code P406 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0406 Code?

Here are the possible reasons why the sensor is sending high voltage signals to the PCM:

egr valve of a car
A faulty EGR valve or EGR position sensor may trigger code P0406.

What are the Common Symptoms of the P0406 Code?

Code P0406 may come with performance issues that can affect the driveability of your vehicle, so pay close attention. Be ready for some of these symptoms if you have a P0406 code on your OBD-II scan tool:

How to Diagnose the P0406 Code

The information listed above contains the basics of the P0406 code. If you want to learn more about how to fix code P0406, you must first understand how to diagnose it. To get an idea of what the troubleshooting process might involve, check out the videos below:

How to Fix the P0406 Code

Diagnostic and repair processes for the P0406 code may vary based on the vehicle’s make and model. Fixing this DTC is a task best left to the professionals if you are not that confident with your automotive know-how and DIY skills.

The first step to resolving the P0406 code is diagnosis. Pinpoint the underlying cause of the issue. Then, with the help of online auto repair resources and guides, figure out the correct way to fix the DTC. You can look up confirmed P0406 fixes and other useful information in a vehicle-specific factory repair subscription, such as ALLDATA.

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