my check engine light came on. I went to autozone and had them run the diagnostic.
the number came up P0401, which is a system fault with the EGR.
A couple of questions:
Do I have to stop driving my truck immediately?
What is the cost to fix?

 

What year and engine. Guys need that to help you.

 

how does the truck drive, does it sputter or buck alot. if it doesn't try to get it fixed, but the EGR is not a critical system, it's mainly there for emissions, some people will even use delete plate to bypass the EGR. however you will not pass emissions like this.

 

Oops! That would help!
2006 f-150 4.6 v8

 

The truck is running fine. Will the inspection people simply use the diagnostic for this or will it fail because the emissions are too high?

 

It will fail because of the presence of a DTC indicating a problem with an emissions device.

Causes

A code P0401 most likely means one or more of the following has happened:
The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
There is a blockage in the EGR (tube), most likely carbon buildup
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum
Possible Solutions

In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.
Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
Clean out the EGR valve and/or tubing to remove deposits
Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
Replace the DPFE sensor (with a good quality / OEM one)
Replace the EGR valve

 

at the OP, in english this means take it to a mechanic.

 

Neither are that hard to replace. The OP can search this forum and probably find a step by step instruction with pictures for both parts.

 

All the scenerios mentioned above are correct. BUT, the most likely cause would be that the EGR intakes inside the throttle body are clogged up with carbon. When this happens it throws an EGR valve fault. It is rare for an EGR valve to ever go bad. Check the vacum lines for any visible damage first. Most likely the throttle body needs to be removed, cleaned and then the EGR intakes cleaned. Just use good ol GUMOUT throttle body cleaner. Do a search for egr intake on this site and there are threads with pics on how to do this. OR just take to a mechanic which should be a quick and fairly inexpensive fix. i got a quote of $170.00 including a fuel system cleaning before i decided to do mine myself.

Also it will fail insp. the truck will drive fine, unless the vacum lines are to blame, and your gas mileage will suffer a little.

 

TL, the 2006 is a whole different system than your truck, it has an electronic throttle.