P0401 Which do you think it is?

[mharrison]

I just got a CEL with code P0401 tonight.

According to my friend google:

A code P0401 most likely means one or more of the following has happened:

* The DPF (differential pressure) sensor is faulty and needs to be replaced
* There is a blockage in the EGR (most likely carbon buildup)
* The EGR valve is faulty
* The EGR valve may not be opening due to a lack of vaccuum

Has anyone else experienced this? Which is the most common problem? I recently ( about a month ago) pulled the top 1/2 of the engine apart to replace the PCV hose under the intake. (I have a V6.) Any thoughts on if this may have affected it or not?

 

[SoonerLS]

Wild guess--lack of vacuum. Maybe something is loose?

 

[Quik LS]

P0401 Exhaust Gas Recirculation Flow Insufficient Detected

the EGR is fed from a tube coming off the exhaust manifold. There are two tubes tapped off into the DPFE sensor (pressure/flow sensor). The tube itself ends in the EGR valve.

There also a vacuum line running to the EGR valve.

If you just had it apart - I would recheck those connections.

 

[mharrison]

Well, while waiting for a warm day....today on the way in to work, my car said "ding" and the CEL went away. I will still be checking the components and connections out though.

I just found it odd. This is the first time I have EVER had a CEL go out on its own when I didn't do anything to fix it.

 

[NickLS]

Someone will correct me if I'm wrong, but even though the light went off, the code, that made the light come on, should still be "accessable" if you got the freeze frame data read...

Sorry for the "that doesn't make sense" answer.. but I'd look deeper into it and give you a real answer, but I got a 9:00 meeting and it's 9:05.. GOTTA RUN!!! LvC Before Work