I just got this pulled (for free at Autozone) as a result of a check engine light.

It said

P0401
EGR Flow
Insufficient

How critical is this to fix and how much is it going to cost me?

 

clean the EGR valve, remove it and clean with brake cleaner. that has worked for me a few times

 

Chances are good that your DPFE sensor has gone belly up. The 2001~2002 DPFE's are not reliable. It is not for sure the DPFE, but the odds are definitely in its favor. Replacement cost is about $40~60 and it's easy to install.

 

Sounds great, do you have any pictures of where that sensor is?

 

It's easy to find. Look for two tubes branching off of the EGR tube to a black sensor that's about an inch square with a 3 wire connector going to it.

This is a tube mounted DPFE, not on a Ranger but yours will looks similar.

 

Take it to the dealer, it is under an extended warranty. I got a letter from Ford about 2 years ago, and just had mine replaced about a month ago. I beleive the warranty pushes it out to 5 years or 80k miles. In any case, mine was free at 58k miles.

 

Whats up Carl! Been a while since I have seen you on!

 

Not much, just been busy getting back to regular life after being gone a year. Been too busy to BS on here much, but things are slowing down a bit!

 

Good to have you back with us!