Error Code 406 EGR Positions Sensor

trouble code 406. this indicates the EGR voltage is high! After you had the EGR valve replaced did you reset the ECU?

Hi. The black soot is that your engine is running too rich. I would have checked out the O2 sensor. The O2 sensor tells the computer how much gas is needed to run your car. If the sensor is malfunctioning or dead the computer will make the engine run with more gas (rich) Go to your mechanic and have him run the code scanner. I would also clean out the EGR valve which you can do yourself. Good luck

Without knowing what the actual code is, I can only give you general info.
No trouble code tells the mechanic what the problem is. Only what to test or check. So O'Reilly was wrong if they said the code told them the injectors were clogged. And AutoZone was not right in saying the sensor is bad, the sensor MAY be bad.
The trouble codes direct the mechanic as to what to check by saying the sensor is not sending the right data or signal, or the computer can not control a component correctly. In your case, the EGR sensor measures pressure and flow for the EGR valve. The valve may be faulty, or the sensor, or a hose in between.
So the EGR system would need to be checked out to determine if a component needs to be replaced or not.

Take it to your nearest Autozone they will hook up a code reader for free and give you an idea what turned on your check engine light.

If you have an Autozone close by, run your Voyager over threr and have them hook up the code reader so you can see what the error code is that is causing the check engine light to come on.
This will give you a clue to whats causing the problem. Hopefully it's just a sensor and not a catalitic converter problem.

Good Luck

This code is for the EGR valve, "P0406 Exhaust Gas Recirculation Sensor A Circuit High", this doesn't necesarily mean you need to change your EGR valve but it's probable. Check with your dealer this just might still be covered.

on youe veicle you have to follow procedures to check O2 sensors
voltage to high more than 3.7 volts
circuit shorted or O2 sensor is no good thats for code 138
code 171 contaminated O2 sensor
406 is your EGR system shorted open thats whats probably causing your O2 sensors to contaminated fix the EGR and clean passage way to intake

Go to your nearest autozone. They can scan the error code and tell you what error it is. Once you have that information it will help pinpoint the problem.
Thank you,
Lee

i believe it's a egr system code
I got a 406 witch is egr flow sensor A high voltage
I hope that helps your search

Late suggestion; it may be that the code needs to be reset via a code reader and that the problem will remain in memory until forcibly removed. That is fairly common.