What fixed your egr P0401 problem?

[camrycoupe]

!Newb alert!

I have scoured all the egr and/or P0401 threads just to be overwhelmed by all of the suggestions. I was really hoping I good get some reponses that list the single thing you found that fixed your egr or P0401 problems. I have replaced the VSV for the egr and took apart the egr, modulator, and egr pipe to clean them and still have my CEL on. I reset the CEL after every cleaning and adjustment as well just to have it come back on. Thanks ahead for any and hopefully many replies!!

1994 Camry Coupe
V6 1MZFE

[camrycoupe]

As I mentioned in the prior post I'm pretty new to this, so I need some help interpreting my inspection of the vsv and egr vac mod...

I 3-way connected the egr, vsv, and vac gauge and at 2,800 rpm's there was no movement on the vac gauge.

Then I connected port R of the egr vac mod directly to the intake manifold and rev'd up to 3,500 rpm's again with no movement on the gauge.

Last I connect the egr directly to the intake manifold and car idled rough.

Prior to this I cleaned the egr, egr mod, and pipe. Installed new VSV egr.

Please help me out what to conclude about the lack of vacuum response in the tests.

Thanks!

[71Corolla]

I'm a bit confused by your post. What did you replace? All 3 components? (EGR Valve, VSV, Modulator)

I repaired my 2001 by cleaning the steel inlet pipe on the EGR valve. I recently worked on a 99 which ended up having a bad VSV, so there can be different causes of the same CEL code.

Easy way to test the EGR valve is to apply vacuum to the valve when the car is idling. If the valve moves properly, the engine should run very poorly or die. Do it a few times to make sure the valve is moving freely. You can also by eye watch the valve move as you rev the engine up and down. You can also turn the car off, and apply vacuum to the valve and watch it to see if it moves up and down freely.

If it does, then you have either clogged lines (not likely) a bad VSV, bad connect to the VSV such as a damaged wire, bad connectore etc. or the vacuum modulator is defective. Again, did you replace all 3 components with new ones? If you replaced everything, then the fault may lie in another sensor, or in a worst case scenario the EFI computer.