Possible hack for P0401 OBD code: insufficient EGR flow
New User
Joined: Nov 2012
Posts: 22
Likes: 0
Hi Everyone. I'm new to the forum and this is my first post.
I own a 1998 F150 4.6 4x4 supercab that I purchased new in 1997. It has 385,000 miles on it, uses a little oil, but still runs great.
I first saw the P0401 code back in 2002 and really have not been able to get rid of it. It's really the only thing about this truck, that has stuck in my craw.
Here is all the things I have tried over the years to rid my truck of this nuisance code...
replaced the DPFE.
checked for vaccume leaks. none found.
replaced PCV and hose.
removed and cleaned throttle body ports.
checked for vaccume leaks again. none found again.
replaced EGR valve.
replaced EGR valve exhaust tube and new vaccume lines to DPFE.
replaced MAF sensor.
replaced fuel cap.
replaced oxygen sensors.
Apparently this is my gremlin...and my money pit. So I gave up on it years ago, and just live with it, since the truck runs just fine. You win Ford, I give up.
The hack sounds good to me, just so I don't have to stare at the stupid CEL anymore.
I own a 1998 F150 4.6 4x4 supercab that I purchased new in 1997. It has 385,000 miles on it, uses a little oil, but still runs great.
I first saw the P0401 code back in 2002 and really have not been able to get rid of it. It's really the only thing about this truck, that has stuck in my craw.
Here is all the things I have tried over the years to rid my truck of this nuisance code...
replaced the DPFE.
checked for vaccume leaks. none found.
replaced PCV and hose.
removed and cleaned throttle body ports.
checked for vaccume leaks again. none found again.
replaced EGR valve.
replaced EGR valve exhaust tube and new vaccume lines to DPFE.
replaced MAF sensor.
replaced fuel cap.
replaced oxygen sensors.
Apparently this is my gremlin...and my money pit. So I gave up on it years ago, and just live with it, since the truck runs just fine. You win Ford, I give up.
The hack sounds good to me, just so I don't have to stare at the stupid CEL anymore.
Last edited by PaulMT; Nov 3, 2012 at 02:34 PM. Reason: typo
Fleet Mechanic
Joined: Jul 2010
Posts: 1,354
Likes: 31
From: Winnipeg
A P0104 is not the same as a P0401. You should start your own thread to get better replies. P0104 is for MAF sensor circuit A intermittent. Quickest thing I'd would be looking for is a crack or loose connections in the air intake tube between the MAF and Throttle body. Please start a new thread if this doesn't help.
It is a P0401 insufficient EGR.
New User
Joined: Nov 2017
Posts: 3
Likes: 0
I've done a great deal of reading on EGR systems over the years & never found evidence that the operation or lack of operation of EGR alone affects mileage one way or the other. If the EGR turns on when not called for, the engine may indeed stumble or stall, but that is not my issue. All my references mention that Exhaust Gas Recirculation, when properly applied, decreases NOx emissions at part throttle. EGR is always supposed to be inoperative at idle, so when the engine starts, how can EGR even be tested by the PCM until the engine has warmed and the throttle is then partly opened? I have also read that the modern PCM circuitry will fiddle with the ignition timing and the fuel/air ratio when the EGR flow is inadequate, but that is a different problem, more a problem with the PCM than the EGR, and something I think will indeed decrease fuel mileage as you said. The point of my 'hack' was to keep the PCM from making those unneeded adjustments until I can come up with the $200-$300 my mechanic wants to remove the intake manifold and decarbonize it. I've driven over 100 miles with my 'hack' installed and can't tell anything adverse is going on.
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