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

P0406 This is the generic OBDII Diagnostic Code.  This code deals with signals coming from EGR systems.  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 Sprinter It will work as any other vehicle.  

The EGR system allows a certain amount of the Sprinter’s exhaust to re-enter the combustion chamber, which helps lower the emissions coming from your Sprinter’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 Sprinter

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 temperature
• Omissions are rising

P0406 Causes:  Dodge Sprinter

P0406 will almost always be due to wiring problems or an inoperative EGR Valve.  We’ll go over both of them in better detail directly below.

Poor EGR Valve

You can use a scan tool to tell the EGR valve that it is open if you have one.  It is worth checking the wiring harness to make sure the EGR valve opens.  The EGR valve can be replaced if the voltage reading is acceptable.  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, These are quite affordable.  

The Wiring of Issues

You can start to diagnose P0406 problems in Sprinters by looking at the wiring harness.  The wiring harness connecting to the EGR valve in your Sprinter is the most likely to be the cause of the problem.

The EGR valve is the beginning point for the wiring harness.  Is there any damage to the plug?  If it doesn’t, go ahead and inspect the wiring harness for any damage.  You’ll be looking for frayed wiring.  You should inspect any area where it comes in contact with the frame or engine.

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

It is a sign of a problem with your wiring if you receive 12 volts instead of 0 voltages.  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 always a good idea test the EGR valve and wiring before purchasing a replacement. 

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