Exhaust Gas Recirculation - Insufficient Flow Dected, Error Code P0401

Joined
Nov 27, 2008
Messages
18
Location
Memphis, TN
Hi All,

Just to add my two cents to the volumes of discussion here. I have had the code for two years. Some years ago, I made some minor bolt on modifications to my cruiser and monitored mileage regularly. I believe the error code (in open loop) caused a reduction of about 1 - 2 mpg. Also, in the long run, if I can keep the cylinders running cooler (richer) I would expect less long term wear. Since I do want to keep the cruiser for a number of years. I've had it ten years this month. So I finally decided to do something about it. As I hoped from the discussion here, it turned out to be the VSV. I bit the bullet and had it changed at a local shop. My mileage does appear to be back up to 15 mpg, hopefully it will go up a little higher on the summer formulation.

Matt
 
Joined
Apr 13, 2006
Messages
1,932
Location
vansterdam, BC
seems to be the vsv is the culprit from most of my P0401 research as well. ive had it for the last 6 or so months, and am in no rush to sort it out since ive been averaging 14-15. highest average was in the mid 16s when i first got the truck, before the code came on. dont want to replace anything really, and the only one im willing to shell out money for is the vsv. replacing it seems to be doable without taking the upper intake off. what did they charge you for the re & re? dealership or indy? im thinking if i pull the intake ill clean all the runners and tb, but the lazyness in me just wants to re & re it from underneath.
 
Joined
Apr 10, 2003
Messages
561
Location
Chester, NH
You better feel around under there real good. I split the plenum to do the job and was happy I did as there was a lot of dry rot on the hoses in there. I still don't understand why doing it without splitting the plenum is so popular - well I understand people want to save time but at what expense? There was also a lot of carbon buildup in one of the passages in the throttle body.
 
Joined
Apr 13, 2006
Messages
1,932
Location
vansterdam, BC
did you have to drain the coolant as per FSM? thats the part i dont really want to deal with (again). otherwise its just nuts n bolts.
 
Joined
Apr 10, 2003
Messages
561
Location
Chester, NH
I did not. I missed that step and by the time I saw it - I realized it wasn't necessary. Nuts and bolts yeah - lots of extensions because you have to come at it from underneath. Took me about 3 hrs from opening the hood to shutting it. 8 mos now without a code.
 
Joined
Nov 27, 2008
Messages
18
Location
Memphis, TN
seems to be the vsv is the culprit from most of my P0401 research as well. ive had it for the last 6 or so months, and am in no rush to sort it out since ive been averaging 14-15. highest average was in the mid 16s when i first got the truck, before the code came on. dont want to replace anything really, and the only one im willing to shell out money for is the vsv. replacing it seems to be doable without taking the upper intake off. what did they charge you for the re & re? dealership or indy? im thinking if i pull the intake ill clean all the runners and tb, but the lazyness in me just wants to re & re it from underneath.
The price was pretty steep, $634 with $157 for parts. Based on what others have posted here, it is a pretty lengthy repair. I work long hours and just didn't have the time for it. The truck also seems to idle a little smoother.
 

jfz80

 
Joined
Jun 5, 2005
Messages
11,156
Location
Madison NC
Just curious if you tested the individual components? i just pulled the same code and testing per the FSM and FAQ indicates the vaccuum modulator for me. Its on the way but i held off on the vsv because of how obviously the modulator failed in various tests.

congrats on losing the amber alert on the dash
 
Joined
Nov 27, 2008
Messages
18
Location
Memphis, TN
Just curious if you tested the individual components? i just pulled the same code and testing per the FSM and FAQ indicates the vaccuum modulator for me. Its on the way but i held off on the vsv because of how obviously the modulator failed in various tests.

congrats on losing the amber alert on the dash
I replaced the modulator a few years ago. This was an independant shop, but the tech had previously worked for the local Toyota dealer for ten years and diagnosed the failure.
 
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