Code P0401

[jolson110]

I am the owner of a beloved 95 Camry V6 LE with 185k on it. The check engine light recently came on and since i didn't want to (can't) automatically pay for a dealer diagnostic I used the code reader provided by a friend. The code was indeed a P0401. I did not understand what this "flow insufficient" actually referred to and I'm now worried that my well-cared for car may have a costly issue. I haven't noticed any performance issues, sounds, smells etc.
After doing some online research I'm still unclear if this is something i would need to have a dealer address. I would greatly appreciate any advice on this matter.

[haux]

Originally Posted by jolson110

I am the owner of a beloved 95 Camry V6 LE with 185k on it. The check engine light recently came on and since i didn't want to (can't) automatically pay for a dealer diagnostic I used the code reader provided by a friend. The code was indeed a P0401. I did not understand what this "flow insufficient" actually referred to and I'm now worried that my well-cared for car may have a costly issue. I haven't noticed any performance issues, sounds, smells etc.
After doing some online research I'm still unclear if this is something i would need to have a dealer address. I would greatly appreciate any advice on this matter.

Welcome to ToyotaNation, friend!

Don't go to the dealership unless they are holding your wife/mother/friend hostage.

To my recollection, a P0401 is "Insufficient EGR Flow." This refers to something being wrong with the EGR (Exhaust Gas Recirculation) system. The possible solutions are to replace the VSV (Vacuum Switching Valve) for the EGR valve, the EGR Vacuum Modulator, or clean related EGR hoses if they are clogged.

I had a P0401 not too long ago, along with other EVAP related codes. I went the full route of replacing everything... the EGR valve itself, the EGR modulator, the VSV for the EGR, and all of the related hoses. The cheaper method would be to just clean the EGR valve, the hoses, clear the code and see what happens. If it comes back, then maybe replace the VSV. After that, it should be gone.

If you use the Search feature in the forum, you will find DIY write-ups on how to do some of this work.

P0401 is one of those annoying codes, but it isn't particularly critical. Yes, the dealership will likely charge a few hundred dollars to diagnose and fix the problem. Doing the work yourself can cost you anywhere from $0 - $100.

[hooRAH]

I recently had a "customer", a family member, come to me with a corolla with the same code. The dealership, when they read the code, told him he needed the VSV, EGR valve, and EGR modulator replaced (plus associated hoses) for $900.

Bottom line - they didn't diagnose, they just told him he had to replace everything. It was in their best interest to make the most amount of money with the least amount of diagnosis time, and so thats what they did. Would it have fixed the problem? Sure! But your loss is their gain, and they don't mind.

Do what haux said -clean the egr and reset the code, and go from there. Theres also a pretty simple test you can perform with a section of "clean" vacuum hose and the vacuum modulator to determine if its bad. If it is, replace and go from there. Don't throw parts at it.

[donhuynh]

Originally Posted by hooRAH

I recently had a "customer", a family member, come to me with a corolla with the same code. The dealership, when they read the code, told him he needed the VSV, EGR valve, and EGR modulator replaced (plus associated hoses) for $900.

Bottom line - they didn't diagnose, they just told him he had to replace everything. It was in their best interest to make the most amount of money with the least amount of diagnosis time, and so thats what they did. Would it have fixed the problem? Sure! But your loss is their gain, and they don't mind.

Do what haux said -clean the egr and reset the code, and go from there. Theres also a pretty simple test you can perform with a section of "clean" vacuum hose and the vacuum modulator to determine if its bad. If it is, replace and go from there. Don't thro? w parts at it.

Are you serious? is it a Toyota dealer? sound like " we can fix the car with 12 parts or less"

[71Corolla]

Originally Posted by donhuynh

Are you serious? is it a Toyota dealer? sound like " we can fix the car with 12 parts or less"

When I first bought my 2001, I had the same code. I didn't have time myself to deal with it, so off to the dealer it went. Same thing, they didn't even bother attempting to diagnose what was wrong, gave me an estimate of $800+ dollars to just replace everything related. It could be more I don't remember exactly. I replaced the VSV for EGR, problem never came back.

If you have a 5SFE, I would strongly recommend people relocate the VSV for EGR onto the intake manifold, it's very very easy! On the Gen4's, there is an open spot, 12mm bolt and you're good. On the Gen3's, it's similar you have to unbolt something and use the same bolt for 2 brackets. If you're really lazy, you could just leave the old VSV where it is and just pull off vacuum lines. You will need to cut the lines shorter etc. but it's no big deal just keep track of what hose goes where, they are numbered most likely.

Here's what it looks like on a Gen4. I am not sure about the V6 where the thing is.





edit - on my Gen4 I think I removed the screw and reversed the unit on the bracket so it would sit better.

[haux]

Originally Posted by 71Corolla

If you have a 5SFE, I would strongly recommend people relocate the VSV for EGR onto the intake manifold, it's very very easy!

EGR VSV Relocation

I relocated mine to the firewall. Close enough!

[71Corolla]

Originally Posted by haux

EGR VSV Relocation

I relocated mine to the firewall. Close enough!

That's just as good. Either way, why in fricks sake did Toyota put the thing where they did? It's like they wanted it to fail.

[JohnGD]

There are some simple tests that you can do, with the help of Autozone's free loaner tools. For example, looking at the first picture in Msg#5.

You see that blue round thing on the right with 3 hoses? That's the EGR valve. The top hose, if you remove it and hook up a MityVac vacuum pump (free loaner from Autozone, with deposit), and pull vacuum while the car is running, then the engine should run rough or stall.

If this test works out then you know the EGR valve or the pipes are not the problem. Then you can focus to the components upstream of those.

As others said, I don't agree with throwing new parts at a problem. It's too bad dealers see owners as big, walking dollar signs.

Originally Posted by jolson110

I am the owner of a beloved 95 Camry V6 LE with 185k on it. The check engine light recently came on and since i didn't want to (can't) automatically pay for a dealer diagnostic I used the code reader provided by a friend. The code was indeed a P0401. I did not understand what this "flow insufficient" actually referred to and I'm now worried that my well-cared for car may have a costly issue. I haven't noticed any performance issues, sounds, smells etc.
After doing some online research I'm still unclear if this is something i would need to have a dealer address. I would greatly appreciate any advice on this matter.