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P0401 - Egr Insufficient Airflow


lexus400

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'96 ES. I replaced the EGR valve but am still getting the same code. What should I try next ?

any ideas ?

Bob

theres a EGR position sensor on top of the EGR valve, make sure thats working properly with a volt meter and find the EGR VSV located on the VSV rail on top of the engine by the intake manifold and check the VSV operation, make sure theres vacuum going to the EGR modulator and out to the valve... i've seen a couple of the EGR position sensor malfunction that caused the same problem.

Good luck :cheers:

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1996 es300 doesn't have an EGR position sensor. Check hoe much vacuum you have at the EGR valve, engine hot @ 2500 rpms. More than likely the modulator is bad

modulator is what I meant to say. my 95 es has the same cel right now. I'm scared to buy a new egr and then it may be the modulator, as mentioned.

I don't have a vacum tester, any other way to check it.

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1996 es300 doesn't have an EGR position sensor. Check hoe much vacuum you have at the EGR valve, engine hot @ 2500 rpms. More than likely the modulator is bad

modulator is what I meant to say. my 95 es has the same cel right now. I'm scared to buy a new egr and then it may be the modulator, as mentioned.

I don't have a vacum tester, any other way to check it.

I have a 94 es300 that had a P0401 code and I just replaced the vacuum modulator. I purchased a new one, and before I installed it I compared it to the old one. What i noticed was the diaphragm on the old one was completely dried out. It would not hold a vacuum when applied to the bottom hole. The new one did. If you don't have a vacuum tester just hook a vacuum line to it and use your built in vacuum pump :-).

Just because I am a curious sort I took apart the old one, and it was completely dried up and has some sort of liquid inside it ?? I assume it is condensation, but who knows ??

I was kind of easter egging to figure out what was wrong, but I did get some good info from this site...

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  • 6 months later...

1996 es300 doesn't have an EGR position sensor. Check hoe much vacuum you have at the EGR valve, engine hot @ 2500 rpms. More than likely the modulator is bad

modulator is what I meant to say. my 95 es has the same cel right now. I'm scared to buy a new egr and then it may be the modulator, as mentioned.

I don't have a vacum tester, any other way to check it.

I have a 94 es300 that had a P0401 code and I just replaced the vacuum modulator. I purchased a new one, and before I installed it I compared it to the old one. What i noticed was the diaphragm on the old one was completely dried out. It would not hold a vacuum when applied to the bottom hole. The new one did. If you don't have a vacuum tester just hook a vacuum line to it and use your built in vacuum pump :-).

Just because I am a curious sort I took apart the old one, and it was completely dried up and has some sort of liquid inside it ?? I assume it is condensation, but who knows ??

I was kind of easter egging to figure out what was wrong, but I did get some good info from this site...

could i ask you where is the modulator located on a 96 es300? also there was a link to download a manual for a camry, but since then my pc crashed and lost all the pdf files on the vechile, since the camry is similiar to the lexus. thanks, if you could help. sorry would have sent you a pm, instead of bringing up this old thread, but the site will not allow me yet.

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  • 1 year later...

Here is the repair manual for '92-'96 Toyota Camry and Lexus ES300 in PDF format:

http://www.turboninjas.com/camry/

It helped me a lot to do the testing of the EGR system. Pictures DO help!

Just follow the procedures chart (you can skip the computer test).

Basically, clean the pipes, do vacuum test of you EGR Valve itself and then if it's OK vacuum test the EGR modulator. Most likely

you will fond you problem by those simple tests.

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