P0401 solutions

[RJHR]

Hi all!

Has anyone ever figured this one out, that is, code P0401? I don't want to change three things and clean a bunch more if not necessary.

I have had the "check engine" light come on and stay on for about a week now, I pulled the EFI fuse for 10 seconds to see of it would give me another 4K miles like it has for some others, but no luck.

This afternoon I went out and pulled the sensor immediately opposite the EGR valve on the intake manifold, it was heavily deposited. I cleaned it up and sprayed some carb cleaner into the EGR, and so far, so geoo, but I am wondering if there has ever been a real explanation / solution for the is problem?

Thanks!!

 

[Beowulf]

RJHR,

There have been several things that have resolved a P0401.

First, you need to tell us your year model. We can assume you have a 96 or 97 since those are the 80 series with OBD-II. I don't want to waste my time explaining how to fix a P0401 on the 1FZ-FE engine if you have the V8 in the 100 series.

Do a search on P0401 on this forum and on the SOR link above then post back with your vehicle specifics and any questions you might have.

-B-

 

[RJHR]

B,

I ran the search you suggested several times in the 80 series list, etc in the last week. I have a 1997 FZJ80 (LX450 option).

What I did not see in all of that was any consensus about what the real fix is, it seemed many people replaced several items (EGR, VSV, etc) but no one had the solution.

Thanks!

Rick

 

[Beowulf]

Rick,
How many miles are on your 97?
-B-

 

[Beowulf]

Rick,

The reason you don't see a consensus on a fix is because the EGR system is multi-component and a failure of any one component could result in a P0401. If you are looking for a silver bullet you won't find one for the P0401. The only way to resolve the problem is a systematic approach to isolate the failing component and then clean or replace it. There are 4 major components plus wiring and plumbing and an ECU. The FSM outlines the testing procedures.

This is the voice of experience you're hearing. My truck got a P0401 around 97k miles and I struggled with it for 18 months or so. I don't intend to bore the others with the story as you can read it in the archives. In my case, the failed component was the VSV for EGR. Others have fixed theirs by replacing the EGR modulator and others have been successful by cleaning the EGR modulator and/or the EGR temp sensor. One of the P0401 threads (yes, I know there are a lot of them) has a link to the Autoshop101 pages that discuss the theory of the EGR system. You may find those of interest.

The bottom line is that mine is fixed and the truck has been P0401 free for approx 16 mo (approx 15k miles).

-B-
[fingers crossed]

 

[RJHR]

B,

Thanks, I will run the search for your thread.

BTW, it has 110K.

Thanks!

Rick

 

[Junk]

There is no fix. It has become all-consuming, both of time and money.