P0401 egr code - Toyota Nation Forum : Toyota Car and Truck Forums

Redsw21guy · 06-11-2009, 01:44 AM

Today i have a dtc came on and it turn out to be the p0401 egr flow code. So far i check the following. but code still return. 1998 v6 camry

1) apply vaccum to egr valve with engine running and it does stall the engine when vac. is apply.

2) ohm the egr position sensor and it turn out to be in spec. 2.5kohm.

3) ohm the egr vsv and it was 32 ohm. than check air flow from port e to port g. air was flowing. next i apply b+ and check air flow from e to f. air was flowing from e to f also. so it good

4) remove the egr valve and clean it by spraying carb cleaner into both hole of the valve. my question is that should the fluid be pouring out from one end to the other? because when i fill it on one end it take a while for the fluid to drip out of the other end. is this normal? or should it flow out rigth away?

5) test drive it for about 30min. light still came back on with the same code. p0401.

any idea on what else could cause the mil? does it sound like my egr valve is bad?

thanks.

slpr1mz · 06-11-2009, 04:12 PM

i had this code... except excessive... i tried a different scan tool and it said it was the sensor... pay 35 for the position sensor instead of 30 for the valve... but yea. there will be a leak. i dont exactly remember how much but there was flow. take the cast iron piece off and spray cleaner into that, and into the hole that is on top of the intake manifold. spray cleaner into the throttle body too. just to help clean it out...

Redsw21guy · 06-11-2009, 11:30 PM

anyone else any idea on why the code is still there? Did it sound like i check all the sensor correctly? maybe i miss something.

thanks

DaiFai · 06-12-2009, 02:21 AM

Did you check the EGR VSV?

Redsw21guy · 06-12-2009, 06:04 PM

Quote:

Originally Posted by DaiFai

Did you check the EGR VSV?

Yes

DaiFai · 06-13-2009, 03:26 AM

If you're sure the EGR VSV is working fine and the vaccum hose to the valve is not leaking, it could be the EGR valve binding when engine is hot. Since P0401 is for insufficient flow, and you said the EGR pipe is not plugged. I would consider the valve is no good.

And can you upload a picture of the EGR positioning sensor, there's a updated sensor for 1MZ-FE.

knkreb · 06-13-2009, 11:04 PM

I had a similiar problem just about 2 years ago... IF the VSV is stuck, you will get the EGR valve to flow, but it will flow under all conditions, and not just the prescribed speed and RPM range that it is supposed to open up. If the computer does not see the MAP pressure change when it commands the EGR open, it thinks that it is not working... only problem is: it's working all the time, and the computer doesn't know it. So, it flags it as insufficent flow.

Hope that helps!

DaiFai · 06-14-2009, 04:59 AM

The computer knows where the valve is, because there's a positioning sensor on top. And if the VSV stuck ON all the time, it will cause rough idle, the code will be excessive flow instead of insufficient.

Redsw21guy · 06-14-2009, 06:50 PM

thanks guys for the input. I am going to try putting a new egr valve and see if it will fix it.

knkreb · 06-15-2009, 06:39 PM

Quote:

Originally Posted by DaiFai

The computer knows where the valve is, because there's a positioning sensor on top. And if the VSV stuck ON all the time, it will cause rough idle, the code will be excessive flow instead of insufficient.

I think that there are several verisons of these systems. Mine had no positioning sensor on top. It was a neat fail-safe approach of EGR valve was regulated by the regulating valve, so it never went excessive. It would "function" normally as an EGR, it just did it all the time, instead of prescribed conditions of over 35 MPH, and specified RPM.

This was on a 97 Camry 2.2L IL4.

Redsw21guy · 06-16-2009, 02:31 PM

so it turn out the egr valve was bad, p0401 is gone now. All monitor have ran to completion including egr.