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P0401 & P0404 Code

12K views 10 replies 9 participants last post by  cristango 
#1 ·
My truck through these codes for the first time today. Hauled my drag car last night and when I started up the truck this morning it ran real rough. No engine light came on but I checked it with my predator and it gave me these codes. What is the best way to fix this. It seems to have cleared up for now.
 
#2 · (Edited)
The P0401 is - Exhaust Gas Recirculation (EGR) Flow Insufficient

The P0404 is- Exhaust Gas Recirculation (EGR) Open Position Performance

Here is the DTC Lookup tool- http://www.dieselplace.com/forum/dtc.php (it's located in the LB7 Forum in a sticky. I think they should put it in every engine section).


Do you have your EGR Blocked or unplugged?
 
#3 ·
I just clear them, I have a st8t piped exhaust and my egr is blocked. It usually only happens when i turn the HP up.
 
#4 ·
Get a blocker plate and fingerstick from Kennedy Diesel. That will stop those codes from coming up.
 
#5 ·
you should be able to turn off the egr with your predator. i know i can with mine. same truck as yours.

your egr could be failing, if you block it and unplug it (when cold) and disable the codes with your predator, it won't matter if it is failing or has failed.

good luck
 
#6 ·
If you can shut it off with the predator then no finger stick needed. But a blocker plate is what you need. With the HP up you can force the EGR open without the plate. Is your truck a cali emissions? Ive gotten those codes from my stock tune before but never a change in performance.
 
#7 ·
I am going to order a blocker plate and no finger stick if I can turn it off with my predator. Would this cause the truck to miss at an idle?
 
#8 ·
No it wouln't cause that. That may be a case of harness rub or may need to ice pick # 2 and #7 injector connectors. Do a search for ice pick and injector harness rub. Thats probably what is causing the miss at idle.
 
#9 ·
Mine did that as soon as I put exhaust on. I can turn my EGR "off" but I still get the P0401 code............as far as I can tell it has no effect on performance. I can clear it and it runs the same but will come back after a few minutes of running. No CEL light.......and like I said.......doesn't seem to affect anything. Been running around throwing that code for 3 years !! LOL
 
#11 ·
why and how do you unplug the EGR? I have mine blocked but am throwing the same codes but no CEL and no negative effect on performance. Just wondering if I should unplug EGR so nothing is working in it that shouldn't be or that is not needed anymore. Thanks.
 
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