Engine light came on yesterday, with a code of P0400. Looked thru list of codes on this site, but it is not listed. Can anyone tell me what it is?
Also notice truck started to run a little rough. thinking it might be cracked vacumn line.
Have an 03 Quad Cab 4.7L
thanks for your help.

 

in my chiltons manual it says that the p0400 is an Exhaust gas recirculation flow malfunction. I looked up the code and it says it is a problem with the egr valve, or a blockage in the linewich is vacuum operated so it could be a cracked vacuum line, or the egr valve. Hope that helps!

 

Thank you for the info. tonight after work I'll check the vacumn lines , then go from there. I appreciate the help.

 

well you dont have an EGR so that narrows it down a little.