How to fix/diagnose Code P0401 Toyota - EGR Valve, Vacuum Modulator, Vacuum Switch Valve DIY

[@thegee-tahguy4877]

I looked at my EGR modulator 100 times and never knew there was a filter that could be cleaned in it. Thanks for letting me know.

[@tgmac8288]

Glad to help

[@xthomasnelsonx]

How did you clean it?

[@tedballsak3475]

Excellent video. Had problem with my 97 RAV, turned out to be the vacuum solenoid on the backside of the engine. I purchased a small plug-in camera for my cell phone so I could see what I was doing. It helped immensely, along with this video.

[@SDsailor7]

So what you did was replace the egr vacuum switching valve and the vacuum modulator? And that fixed the problem? Thank you

[@tedballsak3475]

Hey rob, I only switched the vacuum switching solenoid/valve. Have put about 8,000 mi on it so far and it has passed inspection no problems. It is located in behind the intake manifold on the passenger side of the engine. A mechanic at Toyota told me they call that spot the devil's nest. Of course he told me that after I done the job, nice.

[@SDsailor7]

@@tedballsak3475 Hi ted, I bought the egr vacuum switching valve and that one looks like it is hard to get access to replace, did you have to remove the intake manifold? Or is there enough room to get a wrench on the bolt that holds the valve bracket? I also bought the vacuum modulator so i will also replace that one. Thank you

[@tedballsak3475]

I used a 3/8 drive ratchet with a short extension. But I also had to use that camera to see the location. You can see it from underneath the vehicle but I had the advantage of a grease pit to work out of.

[@SDsailor7]

@@tedballsak3475 I had originally bought the egr valve and took the truck to the mechanic and he said that the egr valve seldom fails, he did a quick test and said that the problem was the vacuum modulator and the egr switching valve and he showed me the location of the valve with a flashlight and i saw that it is tucked back in there! He said to return the egr valve and buy the items he recommended so that is what i did. Tomorrow i am going to tackle the job and hope i can reach it. I would hate to remove the intake manifold to be able to reach it. I dont know if i mention it but the engine on my truck is a 4 cyl 2.7 Is that what you have?

[@NINJA2da]

I have a PRIUS 3rd gen and removed the entire EGR cooler for cleaning. I used an extra reach 12 mm racheting wrench for the three nuts in the back and good luck reaching the 4th HIDDEN 12 mm nut underneath the EGR cooler. Good video TGM!

[@zackshick11]

I can’t thank you enough for this video! I’ve been having the problem on my 2001 Camry and could not find the issue. Thanks to you, I now know it’s the modulator. That saves me from spending an unneeded $100

[@cawley345]

Bruh I replaced the egr valve and the code came back after a day I was so mad

[@WalkingNightmare100]

Yeah the most PO401 culprit will be VSV if the EGR Valve and EGR Mod are fine but it's definitely the Vacuum Switching Valve because overtime it'll get too hot and worn out if not taking care of it. Inside of it has a clicking noise that goes through the holes when vacuuming of course which mean it's a good sign but if it doesn't make a clicking noise then it means it already damaged inside the VSV and it needs to be replace a new one. Other than that, sometimes it can cause a electrical problem too which it might messing up the clicking and it won't function right.. Short ananswer: If it makes a clicking noise it's good and if it doesn't make a clicking noise get a new one and replace it.

[@jesusortiz8565]

Great tutorial. exactly what I was needing to fix my Toyota Tacoma 2.4 L with engine light DTC. PO401. Million thanks. for sure I will save some money thanks to you.

[@skywalker6327]

Does simply changing the egr help as well?

[@BigSmartArmed]

LOL make sure to come back when your p0401 comes back on :)))) and it will...

[@rubenmeza5524]

@@skywalker6327 it's either that, the modulator or the vacuum switching valve

[@NINJA2da]

Removing the EGR cooler is no joke. Spent a small fortune buying specialized tools. In retro, would have been better to take it to a mech and see if the mech will remove - clean the darn thing Myself, and have mech put it back together- to save $/time.

[@dvader3000]

What is an egr cooler?

[@elliottsmock3680]

Helped fix my bad idle - thanks

[@12namleht]

That was very helpful for me...once I cleaned the filter on the modulator, the error went away

[@tgmac8288]

Well done!

[@yukiostrachan2048]

What did you use to clean the filter?

[@Ghosts-jx7dw]

@@yukiostrachan2048 ^

[@elgatogordo9523]

Thank you for your informative video. I’ve been chasing the dreadful P0401 code for the last 2 months. I’ll try your troubleshooting procedure and hopefully it’ll be a simple fix. Update: TB port P was clogged. Cleaned the TB and vacuum ports, now working and P0401 code hasn't come back over 100 miles. Time for the emission test.

[@drfalcoew8939]

Great! how was the smog test?

[@elgatogordo9523]

@@drfalcoew8939 Passed smog with no issues last Saturday morning. Went to AAA afterwards and received my 2021 Tags 👍

[@drfalcoew8939]

@@elgatogordo9523 Awesome! congrats my friend. I think I am having problems with the vacuum modulator as well, but I just ordered a new one. Should come thursday. I hate this P0401 code..

[@elgatogordo9523]

Drfalcoew So did I! I’ve replaced the VSV and the modulator thinking that was my problem. P0401 would return after 25 miles 😡 Finally decided to purchase a vacuum gauge and this tool absolutely saved my remaining hairline...Keep me posted what you find and good luck my friend...

[@elgatogordo9523]

@@drfalcoew8939 Any luck fixing the dreadful P0401?

[@joemikos900]

Very nicely done Sir. Thank you for taking the time to make this video.

[@luminositymusic3810]

Joe Mikos outstanding video. That helped me with my car.

[@jesusortiz8565]

Great tutorial. exactly what I was needing to fix my Totowa Tacoma 2.4 L

[@cinnamonpie5971]

Great video, thank you!

[@tgmac8288]

😀You are welcome!

[@mikes589]

Thank you for this video!!!

[@rkgsd]

Great work sir!

[@tgmac8288]

Thank you! Cheers!

[@ABAB501st]

What if everything is good even the vsv switch?

[@samsam-si6zj]

Hi , in my opinion the problem in this case may be in the intake manifold or in the throttle body, it need some clean and also don't forget to check all the hoses between the egr valves , some times these hoses blocked

[@tgmac8288]

Did you perform and check as this video shown?

[@elgatogordo9523]

sam sam Thanks for your input.

[@johnlarsen4455]

could you use this vacum modulator on a 22re engine

[@tgmac8288]

Never tried before. You can try that out and see any priblem or error code will come out or not.

[@dougdrefus3554]

How much vacuum should be at R and P and at what RPM?

[@jumbojoe55]

Did you have a rough idle on a cold start up?

[@tgmac8288]

No. Do you have the Engine Code - EGR P0401 or more?

[@jumbojoe55]

@@tgmac8288 No, just rough idle after starting. Occurs intermittently and usually only the first start of the day. I got one P0304, cylinder #4 misfire when it was cold one morning.

[@tgmac8288]

The following 2 links maybe be helpful to you. kzbin.info/www/bejne/nGLTZmRsi5KCnNU kzbin.info/www/bejne/aH-2iJWYo52BjKs

[@yukiostrachan2048]

How do you clean the EGR vacuum modulator filter if it is dirty?

[@tgmac8288]

One can clean the small piece of filter by submerging it in a small bottle gasoline for over night. Then squeeze all gasoline and dirts out as much as possible. Use a lot of dishwashing liquid in warm water by squeezing the filter to remove as much gasoline as possible. Then rinse with warm water and let dry after. Warning! Gasoline is very flammable! Don't smoke or have any fire near by. Have to do it outside with in open space. Don't bring it inside your house before put in dishwashing liquid/water. Please understand by doing this and you are at your own risk! I won't take any responsibilities for any outcome.

[@yukiostrachan2048]

@@tgmac8288 Thank you so much for responding and for the warning information. I appreciate it!

[@tgmac8288]

@@yukiostrachan2048 Please update and let know how it works out for you!

[@yukiostrachan2048]

@@tgmac8288 It worked out great! My filter wasn't dirty but I needed a new vacuum modulator. And my check engine light went off. I'm so happy. Thanks for your wisdom in thorough video!

[@tgmac8288]

@@yukiostrachan2048 Well done! Thanks for your feedback.

[@Unknowsubstance]

Can someone help me? When I vacuum test tube P it didn't show on gauge when I revved it but when trying tube R it worked. Could it be tube P needs replacing or something else like carbon build.

[@tgmac8288]

You are almost there. Watch the whole video again! Pay more attention after 3:30. "To check & clean up Port "P" and Port "R" to Throttle Body". That should help you if it has a carbon build up problem.

[@Unknowsubstance]

Can I just spray carbon cleaner through the ports? As I don't have any air compressor.

[@tgmac8288]

​@@Unknowsubstance A compressor has sufficient psi to push the sticky dirts/dust out of the passage but not spray can which might make it worse.

[@tgmac8288]

Are you from USA?

[@suicidethoughts8420]

Can I just clean my EGR with out the using vacuum ?

[@tgmac8288]

Check this out. axleaddict.com/auto-repair/EGR-Valve-Cleaning-Procedure-Step-by-Step

[@MR-nl8xr]

That's not something you might want to do.

[@carloswithac]

Thank you! This helps a lot!

[@alexn3742]

I have a 96 celica 1.8l manual and this code came up. I replaced the egr vacuum modulator right away as well ( I dont know much about cars ) So after I've been driving awhile everytime I'm in first it likes to drop like its almost going to stall and I have to end up feathering it to get it in 2nd gear so I can drive smoothly. Again only in 1st do I have this problem , any ideas ?

[@tgmac8288]

Could you perform this video for your Celica instead of Rav4?

[@tampa1255]

@@tgmac8288 how did u fix it same issue

[@tgmac8288]

@@tampa1255 Watch this video and perform as in this video to your car in order to find the fix.

[@The.Dude.Abides.]

Thanks for the video! This really helped me! 👍

[@alaingillot4718]

first class !

[@tgmac8288]

:)🙂

[@bron-828]

Thanks!

[@NIP28]

Already bought and installed a vacum modulator but the light stays on

[@tgmac8288]

Did you mean you still have the Code P0401? If vacuum modulator is good, did you watch and perform after 3:15? It might help.

[@NIP28]

@@tgmac8288 nah... to complicateted.. im not a mecanic..

[@tgmac8288]

You should bring your car to a mechanic instead .

[@personalfunfest]

excellent video!

[@samsam-si6zj]

Very Helpful video

[@tgmac8288]

Thanks for you feedback!

[@SDsailor7]

@@tgmac8288 where you applying air or vacuum to the hoses to remove any blockages? Thank you. Great video!

[@tgmac8288]

@@SDsailor7 Take a good look to this video again. Especially location 3:20 to 4:46

[@carlrudd1858]

what is a Moulator? LOL

[@NKPGarage]

Great video!

[@tgmac8288]

Glad you enjoyed it