I received a P0402 code after replacing the O2 sensor and A/F sensor and feel like I may have an exhaust leak so I double checked the tightness of the bolt and everything was fine. I am running out of ideals on how do deal with this myself and may need to take it to the shop. Any other suggestions on what I can do myself before they rob me over there?
Egr flow excessive
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steezemcqueen
Moderator
First off, tell us what you have. Year, model, miles, engine, trans, etc etc..
Next, 3rd gens do not have a EGR
Next, 3rd gens do not have a EGR
ChildrenOfBodom
Moderator
I had this code once. Check the EGR vacuum lines. Excessive flow could mean there's a leak from the vacuum lines that connect to the EGR. Turns out that one of mine was rubbing up against a metal bracket and wore a small pinhole. If you find a leaking vacuum line, you can buy any length of it at Pepboys or whatever auto stores you have around you.
I've also had insufficient flow, where the little actuator that controls the EGR broke while it was closed.
The only other idea I have is a bad EGR that may have broken while in the open position... which seems unlikely
I've also had insufficient flow, where the little actuator that controls the EGR broke while it was closed.
The only other idea I have is a bad EGR that may have broken while in the open position... which seems unlikely
steezemcqueen
Moderator
Ah crap. i forgot that the 3RZ's have one.
The 3.4 does not have a EGR
The 3.4 does not have a EGR
2000 4runner 4cyl, auto tran, 148k mi. Not sure what else, stock everything except for the car seat. ;-)
I cleaned the Egr filter today because it was pretty dirty , had a tough time blowing through it with the two P and R ports closed. The filter was point loaded pretty heavily so I washed and dried it and rotated it to load the other side of the filter. It was easier to blow through but a little hard to tell considering the hole size is like a micron.
ChildrenOfBodom
Moderator
Cool.
While that's probably a good thing that you've cleaned it, your problem will be elsewhere... restriction would come up as "insufficient flow."
Did you try searching for any leaks? Look for a little vacuum solenoid (mine happened to be green) mounted on the inside curve of the intake manifold. Look for any lines that may be dry or cracked, or something rubbed through.
I've essentially found a few problems but no real smoking gun. Recommend you armor-all and inspect your hoses as often as you can to prevent any issues. See some photos below of some potential problem spots to check.
Potential problem Noted 1:
One of the hoses connected to the EGR Vacuum Modulator looks like it's been wearing a nice groove in the side of some plastic piece for a long time. Considering that there was some ziptied parts (see note 3), this seems to have been "fixed" before. I'm going to replace the hose but I thoroughly inspected it and can't see any pinholes. Think this may have been the problem that was previously fixed.
Potential problem Noted 2:
Some crack on what looks like the intake to the vacuum system (labeled 2) below, hose will be replaced. But if this were the problem there would just be more air entering the system... so not sure.
Potential problem Noted 3:
The Vacuum switching valve was zip-tied to the mounting bracket so I'm going to replace the tubing and remount the stupid thing. but I had trouble getting the electrical clip off so not so sure this is truly the problem because I couldn't really take the hoses off to inspect.
Note 4:
Just something others should check, there is a rubber mount that was cracked to the point of near failure due to the weight of the connected tubes. There's really not a great way to fix this.. I just ziptied it, don't think it was truely a problem but certainly could have developed.
Closer view of note 1:
Closer view of 2:
Wonderful zip-tie job of Vacuum switching valve essentially bouncing around on the engine intake for god knows how many years:
Check if this rubber mounted connection is begining to crack:
Potential problem Noted 1:
One of the hoses connected to the EGR Vacuum Modulator looks like it's been wearing a nice groove in the side of some plastic piece for a long time. Considering that there was some ziptied parts (see note 3), this seems to have been "fixed" before. I'm going to replace the hose but I thoroughly inspected it and can't see any pinholes. Think this may have been the problem that was previously fixed.
Potential problem Noted 2:
Some crack on what looks like the intake to the vacuum system (labeled 2) below, hose will be replaced. But if this were the problem there would just be more air entering the system... so not sure.
Potential problem Noted 3:
The Vacuum switching valve was zip-tied to the mounting bracket so I'm going to replace the tubing and remount the stupid thing. but I had trouble getting the electrical clip off so not so sure this is truly the problem because I couldn't really take the hoses off to inspect.
Note 4:
Just something others should check, there is a rubber mount that was cracked to the point of near failure due to the weight of the connected tubes. There's really not a great way to fix this.. I just ziptied it, don't think it was truely a problem but certainly could have developed.
Closer view of note 1:
Closer view of 2:
Wonderful zip-tie job of Vacuum switching valve essentially bouncing around on the engine intake for god knows how many years:
Check if this rubber mounted connection is begining to crack:
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I've checked all the vacuum hoses and replaced a big one connecting the air box to the main air intake to the system, cleaned everything up, check the tightness of everything, reset the code and the Check Engine Light still came back on.
Are the two ideas above what I should look at next? The first then the second?
Any other ideas?
ChildrenOfBodom
Moderator
What you really need is an OBD-II diagnostic scanner.
When I was testing my EGR, both for excessive and insufficient flows, I watched my EGR temperature.
The temperature would give away whether or not the valve is properly operating. If the temperature continues to rise regardless of what happens, you might need a new EGR solenoid.
I just don't know if an EGR can get stuck open... lol
When I was testing my EGR, both for excessive and insufficient flows, I watched my EGR temperature.
The temperature would give away whether or not the valve is properly operating. If the temperature continues to rise regardless of what happens, you might need a new EGR solenoid.
I just don't know if an EGR can get stuck open... lol
cool, do you recommend a particular one? or is this fine:
Amazon.com: Autel MaxiScan MS300 CAN Diagnostic Scan Tool for OBDII Vehicles: Automotive
I bought an elm 327 blue tooth scanner and didn't really get all that much more information that I already had. Although it is super cool to have the thing and I'm totally stoked on it.
I tried to remove my egr valve today to clean it but had trouble getting the thing off. The hoses where the only things I couldn't get off so I will have to cut and replace as the rubber is difficult.
I also ordered a new egr switching valve as mine was previously zip-tied under the intake.
Any other ideas on this damn p0402 code? If these two options don't pan out I'm probably going to take it in.
I tried to remove my egr valve today to clean it but had trouble getting the thing off. The hoses where the only things I couldn't get off so I will have to cut and replace as the rubber is difficult.
I also ordered a new egr switching valve as mine was previously zip-tied under the intake.
Any other ideas on this damn p0402 code? If these two options don't pan out I'm probably going to take it in.
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RXvedub
New member
when you say EGR switching valve (VSV), your talking about the green one under the manifold? I have the same thing and ruled out the EGR modulator that sits on top of the EGR. Where and how much did you pay for the VSV?
snow junky
New member
put a little e85 in it, that will lean it out:flamethrwoer2: tune up first....
stevec5000
New member
High CO means it's running too rich, air injection isn't working or Cat is bad. It could be due to a bad intake air temperature sensor or coolant temperature sensor that makes the computer think the engine or intake air is colder than it really is or something like that. I would connect a ScanGauge and check all the readings.
