I have taken my truck to a mechanic and he says that he is pulling the code p0406, (EGR "A" circuit high.) He didn't know how to fix it and after checking a few previous threads have checked all I know to check, vaccum lines and such, have come up with no cure. Here is what is happening; when I am driving the engine stutters, either like it is not getting enough gas or is getting to much. I tried applying the accelerator and it doesn't stutter until it gets to about 5000 rpm's. The stutter is very rough and sounds makes the engine shake a bit so i didn't do it to many times. just enough to see if it happened at the same rpm's. I have read other threads involving this exact issue but nobody posted how it was resolved. Any help would be welcome.

Jeremy
Thank you in advance.

 

Code P0406 has a probable cause of the wiring short on the positive side to the EGR sensor. We need more info on what you have: year/engine size/ F150?

 

I'd suspect the DPFE sensor is shorted internally (output to Vref).

Monitor the PID for the output of the DPFE sensor with the ignition on and engine off. If it reads near 5 volts, pull the DPFE electrical sensor and see if the voltage drops. If it stays at the same reading, it's either a harness short or a faulty PCM. If the voltage dropped to near zero, the DPFE sensor is shorted internally.

Steve

 

2002 f150 4.6L 4X4 extended cab. i don' t know if it is the "W" or the "6". I don't even know what those are or stand for. Also try to dumb it down just a little for me. not to mechanically inclined. I'm a sqare peg in the round hole kinda guy.

 

"W" or "6" = the manufacturing plant where the engine was produced. Windsor or Romeo.

The DPFE sensor measures EGR gas flow. Your truck is throwing a code that indicates the computer is seeing a signal from the sensor that is too high for the self-test.

As for your 5K stutter, it is probably something else. Most likely, it is the beginning of a misfire. Ask your mechanic if his scan tool allows him to read real time values (PIDs). If so, he can do the check I posted above. Also, he can go in and look at the MISFIRE PIDs and see which one has been counting up to identify if a single cylinder has been misfiring but has not reached the point of setting a fault code and tripping the CEL yet.

If he can't, time for a new mechanic who is better equipped. A good independent who has Ford diagnostic experience or your Ford dealer would be your best bet.

Steve

 

is it possible for the code to be thrown in conjuction with the misfire?

 

I don't think so , like Steve is saying , it could be two different problems.

The DPFE goes buggy quite a bit, to the point it needs to be replaced. It's a common problem and Fault 406 is pointing in that direction ..

Your stumble sounds like a weak COP .

 

what's a "COP"?? Remember... Sqaure block, round hole;0)

 

Coil On Plug (COP) - There is 8 , one per cylinder..

 

#4 is your DPFE Sensor -

 

So I changed the sensor. The next question I have is willI have to drive around to see if the MIL goes out or should it go out immediately? Or should I have the code reset and then drive around to see if it comes back on?

Again.... Thank you very much for all of your answers.

 

You should always unhook your Neg Cable on the battery before working on your motor , oops - to late

But yeah , pull the cables off for about 15 minutes or so , then rehook and start. It will learn + re-test. If everythings within your PCM's programed parameters, your light will not be illuminated..

 

could his stumble at 5k rpm be the rev limiter kicking in?

 

So I just wanted to say that you guys nailed it. Thank you so much for all of your help. Also just an "fyi" it was the limiter kicking in at 5k. but there was a bad COP that would give me a stutter under a load while driving.

Jeremy