EGR Vacuum switching valve

i have a 2001 tacoma 2.7 4x4 5 speed. Well i have the po402 code and repalce the egr valve but it throwed the same code a few days later. from what i have read a lot of people say to replace the egr vsv. My question is, I can see it up under the intake and see a screw attaching to it, has anyone ever replaced this before and if so, what is the easiest way to do it? Thanks in advance!!

 

I have a similar 1998 2.7 4x4 5spd and went through a similar experience, but with a PO401 (insufficient EGR) not the PO402
I checked everything EGR related and it was still there . I removed the VSV by reaching in from the front and unbolting (blind), I tested it on the bench by connecting 12v power and blowing into the holes to confirm opening. If it is switching between the valve ports when you connect 12v power it is good
Turns out, in my case, it was caused by the Catalytic convertor going out , More, or less backpressure in the exhaust system will trigger the EGR code
but first you need to rule out the VSV
however a MAF sensor problem can also cause the excess EGR code so it would help to rule that out also
the excess EGR code is read by the front 02 sensor
when the Cat gets plugged up it sends a signal change from the front 02 sensor that triggers an EGR code
A defective Catalytic convertor code is triggered when the front 02 and rear 02 are reading the same, which happens when the cat breaks apart , ususally you will hear it rattle like crazy for weeks while it is breaking up, first they melt ( throwing EGR code), then they break up ( throwing cat code)
the 2001 is a little more complicated because it has two cats my 98 only has one , I would guess the first cat would melt out first
but a bad cat is just a possible cause
a $100-$150 scan tool would help a little, but it is only a little help, it tells what the front and rear 02 sensors are reading and what they are telling the computer to do to trim fuel, but it takes experience to know what it means
.......for instance if the front 02 sensor is reading LOW-LOW voltage spikes on the front one but normal ( LOW-LOW) on the rear, and fuel trim is trimming lean, it could mean the EGR is not closing
........if it reads HIGH -LOW front but very LOW-LOW rear, but fuel trim is trimming rich, it could be a plugged cat
(just a for instance)
IF MAF sensor is not reading a change at rev up it could be causing the computer to compensate by trimming excess rich

 

Very useful!! Thanks so much!!

 

There are lots of threads about EGR codes you can research. Here is a current one:
https://www.tacomaworld.com/threads/po402-code.436735/

 

Check parts before replacing.

The EGR Vacuum Modulator has a rubber diaphragm inside that can become brittle and start to leak. A simple test is to apply vacuum to the bottom pipe and verify that it holds vacuum. This is the most likely reason why this part wouldn't work properly.

Check the VSV like Dustrider explained, but it's easier to check the modulator first since it's on top.