Hey guys. I constantly keep getting the SES light 2-3 times a week every time is the same code PO401. I pulled the throttle body and i didn't noticed any carbon build up. I did replaced the EGR in the past and didn't got the code for a while. I haven't had time to test the egr valve again. I have also heard the exhaust to egr valve pipe has a small orifice and it could get clogged too. I have to pull that out and check as well.

The truck is idling fine as far as i can tell and i don't hear any vacuum leaks. any other suggestions besides checking for obstructed pipes or orifices 1st?

 

When you pulled the throttle body did you check the two ports which the gases get from egr valve to throttle body. Both of mine were clogged with carbon. That is what cleared my p0401 code.

 

im almost positive they were clear as i remember blowing air on the egr side and there was no resistance. I'm going to pull it off again tomorrow to recheck because I only remember one port, not two so maybe i missed one.

 

Man you should really take it in, - since you don't do ANY research...you couldn't of.

PO401:

It's one of the most common DTC's.

1. Also you have the 5four. There's no way in hell to plug up ANY ports in the EGR system w/carbon. This is totally a 4six thing do to poor design. Orifice problems generally don't usually occur in either V8's/V10.

2. NEVER blow compressed or attempt to clean the EGR valve. You'll blow the diaphragm immediately...just like that. It non serviceable..can't be done. Doing so will call for yet another PO401/PO402 (poppet failure).

The fix is very easy, - google it.

 

well jbrew i did google some fixes. I did miss the issue been on 4.6L but im not perfect. I never mentioned i blew compressed air or clean the newer EGR(current one). I did it on my older one that got replaced anyway so not sure were are you getting that from.

I do my research before I do things. That's how I fixed my coolant leak coming from a cracked intake last week. I still asked for feedback from this forum and I got some great advice from the members here which gave me a better idea on how to take the intake off.

Sorry i'm bothering by asking questions. I guess I should just go google stuff and don't ask any questions. Thanks.

 

Point was, don't use compressed air in the EGR. Common mistake. At least you took that from it , a bit rebelliously lol.

Most common prob is the DPFE. Could be one of the hoses , but there's a different DTC for that. The DPFE condensates inside and no longer samples correctly.

Has absolutely nothing to do with the way she runs, - just have that annoying CEL until it's replaced.

 

all right so i found this testing procedure online from this website.

http://easyautodiagnostics.com/ford/...e-egr-system-1

I got me a vacuum pump and followed the testing steps. i tested the EGR valve. As soon i apply vacuum the engine starts to stumble but it won't stall. The vacuum needle was steady at all time and i never lost vacuum. So the EGR valve and passages are good.

I found one issue on the next step which is the DPFE sensor. According to the testing procedure when the truck is at idle the voltmeter should read around 0.9 volts. I'm getting 1 volt which is fine. It mentions when I apply vacuum to the EGR valve the voltage should increase between 3 - 4.5 volts. The voltage only goes up to 1.2 volts and it is using a brand new DPFE sensor that I had already had. The procedure doesn't mention anything regardless if the voltage goes slightly up. If the voltage doesn't go up then the sensor is bad or if it goes up then it is good. So not sure if there is another issue here.

I continued doing the testing assuming the voltage was good( which was not) and tested the DPFE vacuum solenoid. It has 12 volts like the procedure mentions. I put my vacuum gauge on the vacuum line that goes to the EGR like it is mentioned. I checked the line for leaks and tested the gauge before i installed to make sure it works. When i went for a drive and I accelerate there is no change on the gauge. After a few times pressing the accelerator and releasing it the gauge will read 5 inhg of vacuum briefly when i initially accelerate but it won't stay at 5 inhg(while i accelerate), it drops immediately to zero. If I accelerate again it will do the same. I drove back home recheck all the connections and tried tried again. I got exactly the same behavior. This tells me the solenoid is bad.

I had an extra solenoid(not new) that i had laying around. I decided to try it out. I got the same results but of course it could be a bad solenoid since it is not new.

I'm wondering why I'm not getting the correct voltage at the DPFE sensor. Could that cause the solenoid to not open correctly?