Hi there i am looking for some advice on what to try next, i am having idle issues with my truck and getting p0405 code. Its a 2002 F-150 4.6 l. I can start it up and keep it running but as soon as i let off the gas the idle goes very low and wants to die, although if i keep idle at normal range with foot on brake i can shift into drive and it will drive normal.maybe a little lack of power but pretty well normal . I replaced the iac valve about 3 months ago and the egr valve about a month or so before that with the tube that goes down to the manifold. Also i just replaced the egr vaccum regulator , and replaced the dpfe sensor but than it actually was worse when i put the new one on and i could not run the truck at all so i luckily returned it at the parts store as a bad part. I cleaned the maf sensor and throttle body but i have not actually took ooff the entire throttle body to clean it. I am stuck and wondering if i should bring my truck in which i don't want to do , this is why i am here , hoping that someone has an answer lol. Any idea? The last thing i was thinking was taking the throttle body off but from what i have read most people with clogged ports get p0401 not p0405. So if anyones got any ideas to try i would be happy to hear.

 

Potential causes of a P0405 code include:

Short to ground in EGR signal or Reference circuits
Short to voltage in EGR ground or signal circuits
Bad EGR valve
Bad PCM wiring issues due to chafing or loose terminals

Read more at: http://www.obd-codes.com/p0405
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If it doesn't want to idle, that sounds like something in the EGR circuit is holding the valve part way open. Pull the vacuum hose off the EGR valve and plug it - does the idle pick back up?

 

Ok so i ended up taking the throttle body apart and cleaning it, also i just read your post and tried taking hose off egr valve and plugged with no result, also unpligged pcm and lots of vaccum there, as i mentioned the egr valve was replaced a few months ago. It will run fine for the first start up of the day but after this every start i am working the gas to a normal idle to get it in gear than will run fine other than very low idle.

 

I am new on the forum , i should have posted this in the v8 section , is there anyway i can move the whole thread i think i may get more answers there but i dont want to start a new thread?

 

You can't move it, but you can send a PM to one of the moderators asking them to move it.

 

So i got another new dpfe sensor from ford dealer today only to have the same issue. I did notice today that it looks like the two hose , one about 2 inch and the other about 4 long that go from egr tube to dpfe sensor seem to be the wrong hose and that is why the dpfe may be sending the wrong information to the egr valve and causing it to idle very low and keep giving me p0405. So when i was installing the new dpfe and looking at a diagram about which tube should be hi and ref , anyway the bigger diameter hose as of now is the short hose and the smaller diameter hose is the long one , when i called the dealer the new hoses i will recieve are the opposite , i do not understand this unless the old aluminum dpfe i have heard of had opposite size ports. Anyone have a clue, i hope this works, i am thinking that since the bigger diameter hose is on the smaller port it must be leaking exhaust gas and sending some sort of false reading. Would a leak going or coming from the dpfe senda p0405 code?

 

Did you ever find your problem? Im having a similar issue, I know this thread is old, but I've done everything you had at the time of your post... inckuding removing the entire TB and TB elbow for cleaning.