Back to this great site for some more edumacation.
2002 F150 Lariat SCrew 5.4L 4x4; ~145,000 miles.

Truck was running just fine; In fact, I was on my way to get it inspected and the check engine light came on. One of those "You've got to me kidding me" moments. Skipped the inspection, went on to work and put a scanner on it the next day and pulled:
P0405: EGR Flow Sensor A Circuit Low Input
P1405: Diff Pres Feedback Sens Upstream Hose Off/Plugged

Checked under the hood for anything obvious dangling/disconnected. Found nothing odd, reseated a couple easy hoses. Restart, light is out. Got it inspected after about 60 miles and life is good.
For about two weeks.
Light back on with same codes. Truck still running fine.

After some research here, I went to check the hoses on the DPFE sensor. Looked fine. Went to pull one off and the hose just broke off.
Same with the other hose.

Pictures and Questions follow


Note: the hose was not cracked until I went to pull it off.





Note: Showing the 3/4in or so piece of hose left on the DPFE sensor.


Note: Nipple slightly broken.

Questions:
1. How can I test to see if the DPFE sensor is bad? Wondering if I can just cut the broken part of the nipple off and put on new hoses.

2. What is the secret to getting the other end of the hoses off the silver pipes? They didn't really want to come off. Just pull the snot out of them? What's going to be the secret to putting the new ones on?

3. In one of the posts I read, it was mentioned that clogged catalytic converters could cause these hi-temps and melting at the DPFE sensor. How do I tell if they are clogged?
I see no glowing in the dark after driving a few miles. But there certainly is a lot of snap, crackle and pop going on after turning the truck off.

Thanks for your help.

 

1. Replace the DPFE anyway.

2. Use an Xacto knife or box cutter to slit the hoses then peel them off.

3. Take it to a muffler shop, they have the equipment to test the cats for blockage.

 

A 405 huh, - not very common, - but I bet it's the DPFE setting that DTC. They get all gunked up inside. That is very common.

Could be the connector as well, or a wire. Inspect the connector, the inside catches can snap off. Dislodges the connector pins/blades.

405 tech data, -

http://www.gearchatter.com/viewtopic8861.php

_______________________________________________

I don't see any signs of excessive heat from your pics. In fact it looks normal IMO. The silicone hoses are fairly tight to begin with, - not allot of slack. So where yours broke, - is normal with age.

I'm not sure I would worry about the converters given your description and photo's. Doesn't hurt to check flow or vacuum tho.

I'd replace the DPFE and Silicone hoses for sure, clean and check the connector.

 

Changed hoses and DPFE sensor (119.00 total from local Ford dealer).
No change. Both P0405 and P1405 still there after driving around about 10 miles or so.
Truck runs just fine.

I did not actually clear the code with the scan tool after replacing. I figured if the problem was solved the light/codes would go away on their own.
Any point in clearing the codes and seeing if they come back in 60 miles or so?

The DPFE sensor connector looked fine but I just remembered that I didn't actually clean it at all.

Any more thoughts?

 

I would reset the codes and see if it comes back on. honestly. Or if you leave the c.e.l. on without clearing the codes and you did fix the problem, it will eventually clear itself. If its actually fixed.

 

Disconnect the battery for a few minutes to make sure you clear the codes and start a new relearn strategy.

 

I cleared the codes this morning using the scan tool. I was able to get in about 45 miles trying to find a couple of sleds for the kids to enjoy this NC snow storm with before the snow conditions sent me home. Probably won't get out at all tomorrow. It will be a few days before I get enough miles on it to see what it is going to do.

 

Claiming victory with the new DPFE sensor and hoses.
I've got about 160 miles on the truck after clearing the codes with the scan tool.

One thing I did not do though was cut the hoses to length. Each hose has 3-4in of excess whereas the standard cables were pretty much cut-to-length.
Any issues with the extra length?

Thanks.

 

I wouldn't think so, as long as they aren't kinked or pinched off.