Check engine light - P0401/P0402 (EGR related)

[5.0H]

Alright so I threw a check engine light yesterday so I went down to autozone tonight and had them pull the code. 2 codes - P0401 and P0402.

P0401 - the ECM has detected too little flow on the EGR system (EGR stuck closed)
P0402 - the ECM has detected too much flow on the EGR system (EGR stuck open)

So since these codes are cancelling each other out, it's making me think it's the actual EGR pressure sensor. Anyone have any input they'd like to add? experience? Is there anything I can do to prevent the valve from sticking or do I need to replace it? I'm wondering if it's as easy as shooting some wd40 or something in there but I don't want to do that without knowing it's ok. Any help would be great guys. Thanks

edit: Just some background - less than 1000 miles on new NGK Iridium IX Performance Spark Plugs, livewires spark plug wires, screamin' demon coilpacks, and Flowmaster American Thunder axleback. Car has run so much stronger with these upgrades. It still feels strong but the engine seems to hesitate a bit when I'm applying very little throttle.

 

[Quinchi]

I did the same setup not more than 500 miles ago (NGK Iridium IX, livewires, screamin' demon and Flowmasters). Its running smooth and strong but I have a strange noise while cranking the engine. Like something is hitting something. Feels like the engine want to start earlier idk. There is no noise while the engine is running. But it made me think that I might end up throwing codes like you. I am just waiting honestly. I am also hoping to get some input on this.

Cheers.

 

[5.0H]

I did the same setup not more than 500 miles ago (NGK Iridium IX, livewires, screamin' demon and Flowmasters). Its running smooth and strong but I have a strange noise while cranking the engine. Like something is hitting something. Feels like the engine want to start earlier idk. There is no noise while the engine is running. But it made me think that I might end up throwing codes like you. I am just waiting honestly. I am also hoping to get some input on this.

Cheers.

I hear the same noise actually. It gets faster with more throttle. It's like pinging against something. It makes me uncomfortable as well. I'm switching to dual exhaust in may, adding a CAI and custom tune so hopefully the tune will take care of it.

I did some searching on the forum. Saw that some people said to clean all the plugs and unplug the battery for a half hour. I cleaned the plugs with isopropyl alcohol and the battery has been unplugged for almost an hour and I'm about to go run it for a bit. Update to follow.


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[JimC]

Wow, those are some pricey plugs. I run with the stock autolite 5143 or the NGK TR6 on my car with forced induction - for less than $2 a plug! Why did you buy such an expensive plug?

I have heard of some plugs that have just a little too much reach on them when installed causing a noise. Could that be the sound you are hearing? When you pulled the plugs to clean them did you check for a bent electrode and double check the gap?

 

[5.0H]

The gaps on all of them looked good. I just pulled them again just to be sure. However these plugs had quite a bit of oil on them which makes me a little concerned. I mean, the odometer is at 104k so I really can't be too surprised but still...

I ripped around some local streets after pulling the plugs and cleaning them a second time and the car is pulling strong. I also cleaned all the electrical plugs just to be safe. I ran into issues with my mafs throwing a check engine code a while back because the connector had moisture in it from cleaning the engine bay. Also, no check engine light after resetting the ECM either. Let's hope the morning commute goes smoothly tomorrow.


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[5.0H]

Here's a picture of one of the spark plugs uncleared. As you can see quite a bit of oil.

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[TexasBlownV8]

A couple of things about the egr...
First, you say you have oil on the plugs, you may have a lot of oil on the egr tube and components connected to the intake past the throttle body (the egr module is bolted to the intake manifold there on the driver side, of course). Oil gets in there from the PCV hose coming from the passenger valve cover, and it can gum it up.

Second, since you mentioned doing the plugs and all, check the wiring connector to th egr module, make sure its still connected.

Third, You could (should) pull of the egr assembly and check it if you can.

Lastly, if you need a replacement, I have one for sale from a 4.0 that had 42k miles on it. PM me for details.

This is what they look like, you can see some carbon/oil buildup on the tube on the left. That stuff cleans off of course.
http://i224.photobucket.com/albums/dd92/texmike_photos/mustangparts/V6EGRmodule-2.jpg

 

[5.0H]

A couple of things about the egr...
First, you say you have oil on the plugs, you may have a lot of oil on the egr tube and components connected to the intake past the throttle body (the egr module is bolted to the intake manifold there on the driver side, of course). Oil gets in there from the PCV hose coming from the passenger valve cover, and it can gum it up.

Second, since you mentioned doing the plugs and all, check the wiring connector to th egr module, make sure its still connected.

Third, You could (should) pull of the egr assembly and check it if you can.

Lastly, if you need a replacement, I have one for sale from a 4.0 that had 42k miles on it. PM me for details.

This is what they look like, you can see some carbon/oil buildup on the tube on the left. That stuff cleans off of course.
http://i224.photobucket.com/albums/dd92/texmike_photos/mustangparts/V6EGRmodule-2.jpg

Alright I'll rip into it tonight or tomorrow. If I need a new one I'll definitely snag yours. I'll let you know.

Check engine light came back on while driving home today.


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[5.0H]

Alright does anyone know how the fuck to get this guy off? I'm thinking it has just rusted itself on there but I'm torquing the piping when I wrench on the thing. I dont want to mangle anything in the process obviously. There are two bolts that hold it in place to the intake but I left those in until I can get the rusted guy off. Wtfffffff

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[5.0H]

Nevermind I got it...had to use my big boy muscles


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[TexasBlownV8]

Oh crap; that's mofo is ruuusssttt ssteeeeeeeeeyyyyyyyy

Yeah getting that pipe nut loose can be a real PITA. I used a big crescent wrench and a pipe extension on the handle.

 

[5.0H]

Tell me about it. It's hideous to look at. I also think your EGR is a different model than mine. My car is an 05.

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[TexasBlownV8]

So was mine. '05 4.0L.
Same part number (5R3E-9Y456-AA). Different lots/manufacturing dates.

 

[5.0H]

Mike - part arrived today and went in with no issues. Car feels good and no more check engine lights. I even took it for two 0-100 pulls on a back road nearby and it pulled strong and I got no lights on the dash. thanks for stepping in to help and lets hope this solved the problem once and for all

 

[5.0H]

Also here's a picture of the valve I had in my car when I pulled it...just a little bit of build up lol

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[06LimeGT]

looks like it was up your butt lol jk

 

[TexasBlownV8]

Glad you got the part so quickly and it worked out; glad I could help.

Yeah those tubes get nasty like that...as will the back of your throttle body blades, but not as bad.

 

[Quinchi]

Good to see you fixed the issue man.