Throwin a P0401 code

slowbooster

Active member
Joined
Dec 4, 2003
Location
Manchester, CT
TDI
03 Golf GLS
Last Firday on my way to work the CEL comes on, pull the code and get P0401. I clear the code, on my break the code comes back, but when I went home the light didn't come back on. The next day it comes back on and seems like it is here to stay.

I cleaned my intake over the summer, maybe 4 1/2 months ago, so I don't think it needs to be cleaned already. Didn't clean the egr cooler though so I guess that could be a problem.

Anyone have some kind of direction of what I should be checking next?
 

CoolAirVw

Vendor
Joined
Nov 9, 2005
Location
Kansas City Missouri
TDI
Jetta
Sorry I have no help, but I would suggest that if your posting a code number that you shouldn't assume that everyone knows the definition. This happens all the time.

Post the definition with the code.

I know 401 is egr related, but I dont know the exact definition, obviously I cant memorize every code, on every car, and for the New folks I'm sure they would like to understand better what they are reading.

Folks also sometimes post the definition without the code. This is also a "no-no". For instance saying you have a EGR code isn't ok, because there are many EGR related codes.

Oh, and year make and model helps.. Also your location might allow someone to say, "I'm near you, I'll take a look at it."
 
Last edited:

nhdoc

Veteran Member
Joined
Dec 14, 2009
Location
Nashua, NH
TDI
'01 GLS NB TDI 5 Speed
401 is the code for "insufficient EGR flow" or the like...the first thing I would do is pull the hose off the EGR valve and test it with a mighty-vac to see if it holds vacuum and appears to be opening. If that passes then you can T in a vacuum gauge and see if the control valve is sending any vacuum to the EGR valve. It could be something as simple as a cracked/leaky vacuum hose.
 

slowbooster

Active member
Joined
Dec 4, 2003
Location
Manchester, CT
TDI
03 Golf GLS
my bad, it's an 03 golf.

want to tell me that I should search the forum first before starting a thread that has been discussed before?


the code says egr insufficent flow.

I just checked the N18, the resistence flucuaites between 18-16
 

slowbooster

Active member
Joined
Dec 4, 2003
Location
Manchester, CT
TDI
03 Golf GLS
THE RESOLUTION TO MY PROBLEM

When I had my timing belt done, last spring, the vacuum pump line had broken at the nipple to the vacuum pump. The line was able to stretch back over the nipple with the broken piece removed with no adverse affects. Last night, my brake pedal felt stiffer then normal and the car didn't seem to have the same amount of boost that it usually had. With a slight guess I replaced the vacuum pump line, from the vacuum pump to the brake booster, and that has seemed to resolve the CEL problem. The light came right back when I started the car after the replacement, but after driving short distances all around town today it has yet to come back. ::knocking on wood::
 

sfierz

Veteran Member
Joined
Jan 21, 2001
Location
Rockford, Illinois
TDI
1996 Tornado Red Passat
It looks like I may have to replace this line, too. Mine broke off at the nipple when I was removing the cowl on a New Beetle. I have it epoxied now so I hope that will hold up.
 
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