P0401 code
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More Turbo
Joined: Nov 2005
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From: Punta Gorda, Florida
P0401 code
I've got a 96 Ranger with a 3.0 v6 auto. Don't know the exact mileage as the odometer stopped working some time ago it is well over 100,000 miles. I’ve replaced all the plugs, wires, O2 sensors, synchronizer, and all fluids recently. In the last couple of weeks the cel light has come on. The code that was pulled was P0401 low flow EGR. The truck idles like hell when you first start it and doesn’t run much better. It smoothes out some under acceleration, but still runs rough. Feels like I’m missing a cylinder or two. I know that the P0401 code can be several things not just the EGR. Any ideas on how I can narrow down the possibilities.
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Joined: Jan 2004
Posts: 13,851
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From: SW Va
Well at idle you shouldn't have any EGR, so that along with the P0401 code & the rough driveability you've reported, kinda makes me want to suspect a EGR system vacuum leak of some sort.
So I'd maybe first look for loose, cracked, split, or otherwise damaged vacuum lines in the EGR system.
If you don't find any, then you could try disabling the EGR valve by pulling & plugging it's vacuum control hose & see what kind of changes come about at idle & when driven.
If there is no change, then follow the EGR valves vacuum line back to the VSV that controls the EGR valves operation & check it for vacuum leaks. I'd chack the DPFE sensors hoses too.
There is a EGR system guide in this forums "Tech Info" thread, located atop the forum, that has helpful info in it, so be sure to check it out too.
If you don't find anything there, then begin a general engine compartment search for loose or damaged vacuum lines to all systems that use vacuum in their operation.
Just some ideas to ponder.
Let us know what you find.
So I'd maybe first look for loose, cracked, split, or otherwise damaged vacuum lines in the EGR system.
If you don't find any, then you could try disabling the EGR valve by pulling & plugging it's vacuum control hose & see what kind of changes come about at idle & when driven.
If there is no change, then follow the EGR valves vacuum line back to the VSV that controls the EGR valves operation & check it for vacuum leaks. I'd chack the DPFE sensors hoses too.
There is a EGR system guide in this forums "Tech Info" thread, located atop the forum, that has helpful info in it, so be sure to check it out too.
If you don't find anything there, then begin a general engine compartment search for loose or damaged vacuum lines to all systems that use vacuum in their operation.
Just some ideas to ponder.
Let us know what you find.
New User
Joined: May 2008
Posts: 22
Likes: 0
From: SW Lower Michigan
Sounds like an ever common problem with the Ford Trucks. I replaced the pressure feedback sensor on my Ranger twice now in just a few months. It runs fine for a while and then back to rough running at the sweat spot. Sweat spot is on level ground maintaining the speed. Going up a hill or down a hill, the engine runs fine. The engine really runs rough around 1,500 rpm's. Even more so after shutting off the engine for a few minutes and then starting it back up. My truck idles fine though. After a long drive it clears up. It seems to me the electrical soleniod that controls the vacuum to the EGR valve may be sticking.
I tested the EGR valve with my hand vacuum pump and it opens and closes very smoothly.
I have a 2001 Ranger, standard cab - short bed, 4x2, 5-speed OD, 3.0 Litre V-6.
I tested the EGR valve with my hand vacuum pump and it opens and closes very smoothly.
I have a 2001 Ranger, standard cab - short bed, 4x2, 5-speed OD, 3.0 Litre V-6.
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