EGR Insuffient Flow. P0401

I pulled out the EGR today and made sure it wasn't stuck shut or open. I cleaned it out as well as grinding it down and replacing the gaskets. The EGR modulator has a filter inside of it and it's dirty. Any clue where I can get another filter? Toyota only sells them as a whole piece. 67 dollars at my dealer price. I'd have to buy the whole modulator. Is there something I can maybe make the filter out of?

 

Just clean it and re-use, but I really doubt thats the issue.
Likely culprits are the modulator itself, the VSV, or the temp sensor (that was my issue when I had a P0401).

 

Well, 60 miles and the code is still gone

 

if you get to 200 miles and no code then your good, it usually takes 100-150 to pop a code

 

I'm not sure what specific code that Keakar has actual experience with, but I don't think this generality is true. My experience is with this exact code.

When I first got the code, I replaced the modulator, and the code came back in a day or so (about 60 miles). I cleaned/replaced the sensor, and it took couple of months (maybe 800 miles) before the code came back. Then I did a more thorough cleaning of the sensor (including using a small hammer and chisel) and the code never came back. If the code ever pops up again, I'll break down and spend the $$ for a new sensor.

 

the way the ECM works is it reads a sensor somewhere is "out of spec" but it doesn't pop a code yet because it might be a false reading and if it popped a code with every out of spec reading it got you would have codes flashing all the time driving you nuts when nothing was wrong, so it waits for confirmation that you do have a real issue by waiting to see if it gets the same code for the same issue again two more times before it lights up the code.

this means it usually takes an average of 3 start, warm up, run a few minutes, and shut down cycles to register or if it is continuously running, such as you just get in and drive, it waits for either a set time period or distance of still seeing the "out of spec" reading, to light up the code, im not sure which. for the average person, 3 driving cycles usually gets yu in the 100-150 miles traveled range which is why I said if you make 200 miles then the issue is no longer registering with the ECM as "out of spec" so you are good.

 

Well Karl, you are partially correct. My factory Toyota manual refers to this as '2-trip detection logic'. Many codes, including the P0401, use this logic, to eliminate what I would call 'hicups'. However, this does not apply to all codes. Many do not ( P1335 for example ).

 

thanks, always glad to learn new things, I thought that applied to all codes

 

Just got the code at 80 miles

 

could you have some how messed with the 3 vacuum lines on top of the TB? I got mine crossed once and it kept throwing not enough egr flow code

as it turned out, I just had put them back in the wrong order after cleaning the TB

 

No, I took pictures