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P0401 Code

S

screechingdemon

New member
I recently had a P0401 code show up on my 99 GTP. I pulled the EGR, cleaned it and put it back in and a couple days later the code was back. I next went ahead and replaced the EGR with a new GM one and that worked for about a week and then the code was back again. Last night I pulled the metal flex tube from the EGR to the intake and cleaned it as well as the EGR port, but they weren't plugged or really that dirty so my guess is the issue will come back, what else do I need to look into on this?
 


If you aren't interested in deleting or shooting in the dark, we can take a minute and learn what the code really means. Because it's common when you get a flow issue with an EGR that it's not the valve. Which means deleting the valve isn't fixing the root of the problem and your motor may pay the price down the road.

GearChatter.com :: View topic - DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient

Take a read into the diagnostic aids.

What I get from the link is this..
Check the map sensor and it's vacuum connection. Because...that's how the EGR flow is read by the pcm.
Check that egr to lim tube that always has a crack in it around the edge by the LIM. Ok, 80% of the time. Ask me if you don't find a crack and I'll describe better where it's located.
 


BillBoost37 said:
If you aren't interested in deleting or shooting in the dark, we can take a minute and learn what the code really means. Because it's common when you get a flow issue with an EGR that it's not the valve. Which means deleting the valve isn't fixing the root of the problem and your motor may pay the price down the road.

GearChatter.com :: View topic - DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient

Take a read into the diagnostic aids.

What I get from the link is this..
Check the map sensor and it's vacuum connection. Because...that's how the EGR flow is read by the pcm.
Check that egr to lim tube that always has a crack in it around the edge by the LIM. Ok, 80% of the time. Ask me if you don't find a crack and I'll describe better where it's located.
Click to expand...

Your talking about the metal flexible tube from the EGR to the intake right? I had it off last night and never noticed any cracks in it. Also what kind of seals/gaskets need to be on each side?
 
I kinda feel like you didn't follow the link. Please do, it's tough for me to push that on you w/o seeming like I am. I once saw a guy spend $400 on EGR's because folks shot in the dark on a forum that I wasn't welcome at. When the guy came to me with the code, I looked it up and found it to be flow. Then he said "I glued my map when I was doing..." A $20 sensor and it was fixed.

Pull the EGR to LIM tube again. Where it goes into the LIM, pull the part that is held by the bolt back down the tube a little bit. Now look at the tube where it starts to flare out. That's the typical area for a crack. It's also easy to hold it up for light to shine in there. If you see light..you have a crack.
 
I had already checked the majority of the items in the link, but went ahead tonight and went thru it all and the only thing I found was that on both ends of the tube from the EGR to the intake had very small cracks running parallel with the flare, I didn't even notice it last night when I had it off. I thought about trying to JB weld them or seal them up but a new tube is only $25 and the local dealer will have it by Friday so hopefully that takes care of the problem. Thanks for your help.
 
Typically the EGR tube at the point which you describe it..won't cause the issue. Have you done anything near the map that might have sent it to it's grave?

On the tube. I've seen people try everything. The only item that works is a new one.
 
BillBoost37 said:
Typically the EGR tube at the point which you describe it..won't cause the issue. Have you done anything near the map that might have sent it to it's grave?

On the tube. I've seen people try everything. The only item that works is a new one.
Click to expand...

The only thing I did to the car before this started was the weekend before I replaced the air filter. Wouldn't I be getting an additional code or have drive ability or running issues if it was the MAP? Car runs good, fuel mileage is still good, I just have the annoying code that keeps coming back.
 


Not necessarily. I've seen it go this way. Looks like EGR, must be EGR. yet it ends up being the item that checks the flow of the egr.

The air filter change caught my attention. What did you change there. Standard panel swap out, new k&N, recharged oil filter?
 
BillBoost37 said:
Not necessarily. I've seen it go this way. Looks like EGR, must be EGR. yet it ends up being the item that checks the flow of the egr.

The air filter change caught my attention. What did you change there. Standard panel swap out, new k&N, recharged oil filter?
Click to expand...

Just a standard air filter, nothing special.
 
went about a week without the code and then it showed up again today. the check engine light came on, but then went back off. I read the codes and had P0401 again. Could it be my MAP, PCV or MAF sensors? I am really not sure where to go from here with it. Guess it doesn't seem to affect drive ability, but I would like to get rid of the check engine light.
 
Hold up on the maf and iac.. those aren't part of this according to the links diagnostic aids.

Check your pcv and map sensor.
 


I took a look at the PCV and it was an oily mess and only a couple bucks so I went ahead and replaced it. I also pulled the MAP and looked at it and it looked ok, not sure how you determine if it is bad or not, at least I don't have a tool to do so. At $50 for the sensor I was tempted to just replace it, but decided to wait and see if the PCV did anything. I also followed the vacuum line from the MAP all the way around the engine and found a couple rubber joints that may be suspect, didn't get any change when I sprayed around them with carb cleaner when the engine was running, but I did go ahead and replace them so I don't have to deal with them in the future.
 
screechingdemon said:
I took a look at the PCV and it was an oily mess and only a couple bucks so I went ahead and replaced it. I also pulled the MAP and looked at it and it looked ok, not sure how you determine if it is bad or not, at least I don't have a tool to do so. At $50 for the sensor I was tempted to just replace it, but decided to wait and see if the PCV did anything. I also followed the vacuum line from the MAP all the way around the engine and found a couple rubber joints that may be suspect, didn't get any change when I sprayed around them with carb cleaner when the engine was running, but I did go ahead and replace them so I don't have to deal with them in the future.
Click to expand...

Code came back yesterday, not sure what is next.
 
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