Dodge Magnum P0406: EGR Sensor “A” → Circuit High

P0406 This is the generic OBDII Diagnostic Code.  It refers to the EGR signal.  In this case, it means that the signal coming from the EGR system is higher than the specified range  Since it is a generic code, it has the same meaning for the Dodge Magnum As it would for any other vehicle.  

The EGR system allows a certain amount of the Magnum’s exhaust to re-enter the combustion chamber, which helps lower the emissions coming from your Magnum’s exhaust.  When the EGR system has an issue, usually the only thing you’ll notice is the check engine light.  

P0406:  EGR Sensor “A” → Circuit High

P0406 Symptoms:  Dodge Magnum

Since the EGR valve is part of the emissions system, there aren’t always symptoms associated with P0406 (other than the service engine soon light).  

These are some of the symptoms that are most commonly associated with P0406 if they're present.

• The engine can be slowed or raked.
• Check engine light
• Higher combustion temp
• Emissions have increased

P0406 Causes:  Dodge Magnum

Nearly all cases of P0406 are caused by wire issues or bad EGR Valve.  We’ll go over both of them in better detail directly below.

Bad EGR Valve

A good scanner tool can be used to force the EGR to open.  It is worth checking the wiring harness to make sure the EGR valve opens.  It is possible to replace the EGR valve if it's OK.  There’s plenty on testing this wiring in the next section.

CarbonEGR circuits can be stuck by junk and even ice.  P0406 can be caused by the EGR valve.  Blindly replacing it without testing can lead to a costly repair.

If the EGR valve is installed, They are very affordable.  

Problems with Wiring

You can start to diagnose P0406 issues in Magnum Magnum by looking at the wiring harness.  The wiring harness connecting to the EGR valve in your Magnum is more susceptible to failure than any other wiring.

Locate the EGR valve where the wiring harness begins.  Are there visible damage signs on the plugin?  If it doesn’t, go ahead and inspect the wiring harness for any damage.  You’ll be looking for frayed wiring.  It is important to inspect every place it touches the engine or frame.

To check the voltage at the harness, you’ll need a volt meter.  You should also check the voltage in the reference circuit.  If it’s at 5 volts, but the EGR Valve won’t open, that’s a pretty good indication that the EGR is bad. 

A wiring problem is indicated if you have 12 volts and 0 volts.  Here’s a great writeup on diagnosing your wiring issues Source: AA1Car.com

Conclusion

Most of the time, when P0406 is thrown, it’ll be the EGR valve that is the cause.  However, it is still recommended to check the wiring and test it before purchasing a replacement. 

Please leave comments below if you have any suggestions.  We wish you all the best in diagnosing your Magnum.