Join Date: Nov 2012
Location: Vacaville, ca
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Need help, Have a reoccurring CEL on my ’04 F-250
Been getting P-401 forever, but now that California wants diesels smogged I need to get it fixed. This code keeps popping up no matter what I have done i.e. replaced EBP, MAP, MAF, EGR valve ( even cleaned several times), no leaks in the intake or exhaust.
Only upgrades so far have been Bullet Proofs Oil and EGR coolers ( not a delete ) and ARP head studs. Bought Auto Enginuity for my truck and noticed an issue.
While out driving and troubleshooting the EGR valve I had the EGRVP and EGRVPDES on the AE and noticed that at first the two would track together but for no reason the EGRVP would just go to 0% even though the EGRVPDES was still working trying to command the valve to open( MAL did not come on yet). Truck would sometimes start and run with them tracking and sometimes they would not (EGRVP = 0%).Other times it would start without them working. Its just hit or miss when they work, not work, work again. The weird thing though is that when the EGRVPDES was trying to command the valve to open and it would not, I could command it to open manually with the AE ( IAT2 temp increases).
I’m 99% positive this is what’s causing my P-401 code. My first thought is that maybe the PCM needs to be reflashed or the PCM itself is bad. Need help before I drop $1000 for new PCM and flash.
Last edited by Aeromac69; 07-09-2013 at 05:33 AM.