Annoying P0401 Code
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Annoying P0401 Code
Hi All,
I recently had my HPOP and IPC replaced on my 2004 F250 6.0L. Since then it has been throwing a P0401 - Insufficient EGR flow error. I replaced the EGR valve and I still get it. The truck runs fine but the CEL drives me nuts. Any ideas on what to check for now?
Thanks!
I recently had my HPOP and IPC replaced on my 2004 F250 6.0L. Since then it has been throwing a P0401 - Insufficient EGR flow error. I replaced the EGR valve and I still get it. The truck runs fine but the CEL drives me nuts. Any ideas on what to check for now?
Thanks!
Hotshot
Joined: Jun 2006
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From: Hampstead, NC
There can be a few causes for this.
Did you make sure the intake was clean when the EGR was out? Could have a wiring problem, could have a MAP sensor problem or clogged hose going to it. Anyway to look at data?
Did you make sure the intake was clean when the EGR was out? Could have a wiring problem, could have a MAP sensor problem or clogged hose going to it. Anyway to look at data?
Elder User
Joined: Aug 2007
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From: Milwaukie, Oregon
I have seen this many times. On high mileage vehicles I have actually seen egr coolers that are plugged with carbon restricting flow. But the other thing I have seen that can cause this is a dirty mad sensor usually from lack of air filter maintenance. It will set a p0401 when the egr valve is open and the PCM is expecting to see a lower maf reading from less intake air entering the engine due to the egr gasses taking up that space in the intake stream that the normal intake air would be. Make sense?
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Thanks. I pulled the IAT2 and cleaned it. It wasn't caked with carbon at all. I have yet to look at the MAP. I'll do that this evening. Also the old EGR valve I pulled off was fairly clean too and the EGR cooler was not clogged.
Even though I cleaned the IAT2 would it be better to simply replace the IAT2 and MAP?
I can clear the code and The light might stay off for 20 miles and then reappear. It doesn't immediately reappear.
Also I can look at data.....
Even though I cleaned the IAT2 would it be better to simply replace the IAT2 and MAP?
I can clear the code and The light might stay off for 20 miles and then reappear. It doesn't immediately reappear.
Also I can look at data.....
Lead Driver
Joined: Feb 2011
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From: L.A. (Lower Alabama)
I have seen this many times. On high mileage vehicles I have actually seen egr coolers that are plugged with carbon restricting flow. But the other thing I have seen that can cause this is a dirty mad sensor usually from lack of air filter maintenance. It will set a p0401 when the egr valve is open and the PCM is expecting to see a lower maf reading from less intake air entering the engine due to the egr gasses taking up that space in the intake stream that the normal intake air would be. Make sense?
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Elder User
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I have my money on the maf sensor. The engine isn't delivering enough fuel to get more boost because it thinks not enough air is entering the engine. Also in factory training they say to never try to clean a maf sensor. I've done it before but it never was dead on after that. It read better on data logger but was still a little off. Fuel pressure good?
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It was a community short bus for elderly and handicapped people to get around. Lots of idle time.
Postmaster
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From: Houston, TX
Hi All, I recently had my HPOP and IPC replaced on my 2004 F250 6.0L. Since then it has been throwing a P0401 - Insufficient EGR flow error. I replaced the EGR valve and I still get it. The truck runs fine but the CEL drives me nuts. Any ideas on what to check for now? Thanks!
Dom
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Elder User
Joined: Aug 2007
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From: Milwaukie, Oregon
You will have more codes then just p0401 if there is an electrical concern
Postmaster
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From: Houston, TX
Dom
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Postmaster
Joined: Jul 2011
Posts: 3,263
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From: Houston, TX
Hi All,
I recently had my HPOP and IPC replaced on my 2004 F250 6.0L. Since then it has been throwing a P0401 - Insufficient EGR flow error. I replaced the EGR valve and I still get it. The truck runs fine but the CEL drives me nuts. Any ideas on what to check for now?
Thanks!
I recently had my HPOP and IPC replaced on my 2004 F250 6.0L. Since then it has been throwing a P0401 - Insufficient EGR flow error. I replaced the EGR valve and I still get it. The truck runs fine but the CEL drives me nuts. Any ideas on what to check for now?
Thanks!
to everybody else att reads this…….just food for thought…..if his problem isn't an electrical problem, why the code? tat code is something to do electrically. just food for thought. don't kill me now. lol. it's a sensor thing. somewhere a sensor is telling a computer tat there is not enough air flow past egr valve.
don't mean to second guess anybody else, but if maf sensor, won't he also be throwing other codes as well? just curious.
and if his truck is truly not pulling in enough air thru intake and somehow the maf sensor is throwing tat code, won't the truck be running rougher than usual? for lack of air, to put it bluntly. i think it would also be throwing some sort of "lean" codes too. i think.
just throwing it out there. no need to crucify me. i'm just being annoyingly inquisitive tonight. lol.
