Compression Ignition Addict
Join Date: Sep 2010
Location: Trophy Club, TX
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Getting P0401 AGAIN...What are the causes?
A little back story. My truck is at 110K miles, I bought it 11 monhts ago at 97K miles, and the only thing on the Oasis was a new EGR Valve at 92K miles. Within 100 miles of the purchase I threw the wrench light, and the oil cooler was replaced, but I was reassured the EGR cooler was fine.
Jump to January or February of this year and around 101K miles, I did my coolant flush and I received my first p0401 while driving my truck around for the 90 minute warm up period. I had to put Ford Gold Coolant back in as I dumped all my coolant at the start of my coolant flush and after I had talked to an International dealer about having ELC concentrate only to arrive (mid flush) and find out it was 50/50 mix. I pulled my EGR valve cleaned it up real good and the code went away.
Jump to May and 107K miles on the truck and the code started popping up every 10 miles of driving. Finally gave in and took it to the stealership. After of week of back and forth and numerous tests, I was told my manifold was caked with carbon deposits and need to be steam cleaned, and repeatedly reassured my EGR and oil coolers were fine(which is why it took a week, i had them check and recheck). Instead of paying $1500 or so to have them steam clean it, I pulled it cleaned it and put it all back in as well as a new EGR valve(just to be on the safe side).
Since then, all had been well. Then over the weekend, actually the exact moment my truck hit 110K miles, the CEL popped back up with p0401. I pulled my EGR valve to look in the manifold and it is still relatively clean(not spotless, but at least to compared to before I cleaned it). My EOT and ECT have a constant 7-9 degree delta, and never stray from that range. I am not losing coolant. I am not having starting issues. I am not having any smoke out the back. I am on my 3rd EGR valve in less than 20K miles. The onlything I have changed in my truck since cleaning the manifold is the straight pipe exhaust, which was done a couple of thousand miles ago.
So my end question here is, why the heck am I getting this code? What makes the p0401 show up? When I get home tonight, I am going to pull my EGR valve again, and check for moisture, but other than that I am clueless what to look for or where to start. Any direction would be appreciated.
SOLD (and regretting it everyday since)
2006 King Ranch Long Box
DieselSite Coolant Filter
SCT w/custom tunes
4" Magnaflow Straight Pipe
Edge CTS w/EGT
Last edited by astroinhouston; 08-17-2011 at 12:23 PM.