Toyota EGR Diagnostics P0401 

Common issue w/ Toyotas w/ higher mileage. Lots of ways to skin a cat... I start by running car and pump up valve to see if it opens and stalls .To myself removing valve and having to clean passages is the hardest part of that fault. So I test that first. Next I put vacuum gauge on vacuum line to EGR valve and see if gauge detects vacuum under load. If no vacuum then I test VSV. Yes Toyota had a brain cramp when positioning the VSV under the intake where crud,heat is common. Obviously much easier to test and replace on a lift. Ivan you do a great job with all your videos .Thanks for the lesson on how You approach the problems. I find them very useful and it keeps me boned up on my abilities and skills .I truly appreciate your efforts. Thanks !

Thank you for posting. My husband and I do a lot of fixes to our cars. We have a 98 Camry V6. I haven’t seen any videos online that are so easy to follow and in detail. I am pretty sure our Camry has this issue. We will definitely go through your steps. Thank you again.

I always love watching the bonus footage!

Thank you Mr. Pine Hollow! I have the same toyota and the same problem, I'm going to go straight to the problem. Thank you very much!

Dude,I can't tell you how much thanks to you.your trans fix on the pt cruiser trans limp mode issue.hooked up relay just like you did in your video,no more limp mode.Your a steely eyed missile man.Thanks again

Good on her for checking it out before her trip. Now hopefully she takes care of it all before she goes. It's better and cheaper to take care of it on her time versus on the road at an unexpected moment.

Great video. You are clearly a very smart technician. Thank you. You definitely gained a subscribers

Do it right fix all the issues Ivan you are the man happy holidays to you and your family God bless

Yup! Same here... typical Toyota Camry & Solara 2.2L issues. But crazy reliable cars. VSV replacement after replacing EGR, Vacuum Modulator and Vacuum lines. Going to tackle the oil leak later. Mine also has 138,000 miles on her (2000 Solara) I love ❤️ this car. Even after purchasing new vehicles. After VSV replacement- no more “check engine” light!!!!

Awesome. The flow testing was very helpful.

I love the way you do stuff I used to do the stuff same way back in the day thank you and happy holidays

For the people who wants to know how a good diagnosis is made. Follow Ivan.

Thanks a lot. This was a great video to pin point the solenoid test! A+

I had the same code just got a EGR valve on Amazon and it work perfectly 😃

@Ivan great channel. Great diagnosis. Fan of your channel. 👍🏼👍🏼👍🏼

I looked at the diagram, It looks like one hose is Venturi Vacuum maybe for throttle position and the hose farther away from the throttle plate is intake for Load sensing vacuum. Love the show ! We need a Avoca, NY express episode :) like the stanton Isl. express .

good job /good video Merry Christmas to you and your family Ivan !

HOW DOES SHE PASS THE EMISSION TESTING WITH THAT CODE APPEARING. YOU'RE AMAZING... YOU'RE SO HONEST IN YOUR DIAGNOSIS. i WISH YOU LIVED NEAR ME.

My 1995 Sentra had an EGR code when I first bought it years ago. After a visual inspection, I found that the exhaust backpressure tube had burned through after all the years and miles. Without the exhaust pressure, the EGR valve would not open. If I remember right, the Nissan system has a thermistor installed in the intake manifold just after the EGR valve. When the EGR valve is expected to open, the ECM watches for the thermistor to heat up and change in value, indicating that the EGR valve did, indeed, open.

Did hundreds of these when I was at the dealer. Previa was another bad one. My 5 minute check: 1) Apply vacuum to EGR at idle, check for engine stall. (Good) 2) Apply vacuum, usually with my mouth, to modulator. Does it hold vacuum or is it blown apart? 3) Replace VSV if nothing else. High failure rate and they can stick intermittently.

Here's one trick you won't find in the engine manual: check your long term fuel trim when fighting any EGR problem. Why? Because it can provide proof of a vacuum leak, and trim holds positive at idle... dropping off as you rev up, and that leak just may involve the EGR system. After you are satisfied all hoses are good and snug but remain positive [say 1% to 3%] there is only one place left which is un-inspectable except using a vacuum pump to test: the modulator. If diaphragm is damaged/pinholed, the vented filter under that cap can become an unwanted air input to the throttle body, and O2 sensors pickup on a lean condition, forcing ecu to compensate with more fuel above the normal curve. When I replaced my modulator [chasing intermittant P0401 codes], LT fuel trim dropped from a little over 1% to -0,5%. Problem solved.

Ivan Great video Don't forget rear main seal on these Toyota's.

Great Ivan. Merry chrismas and happy new year :)

Thank you very much for showing me where the EGR vacuum solenoid it's located and how it works

Diagnosed the timing belt by ear ! Very impressed,Ivan.

Ivan - you have to rewind the solenoid coil....Great video

Just replaced new egr solenoid and modulator worked fine until keep getting p401 code had to use a Speedo wire to clean the egr tube worked but still getting that error so glad I found here!, now it buying that VSV.. These Y2K Camrys will never die they just keep on riding! Had to change my timing belt (just hit 100k) miles on OG factory belt and new water pump, new timing sensor, now some parts getting worn down that VSV is killing my mpg!! Soon replacing intake manifold for performance, all metal core radiator, fans etc Andy Serkis is that you?

Excellent video . Very clear and quickly gets to the point. I had the same code on my 99 4cyl. I replaced the modulator and it went off on my ride home. Next morning light is on with system too lean. Found a cracked hose from throttle body to air cleaner and replaced it light went off on ride home. Next morning light is on with air fuel sensor slow to respond. Replace o2 sensor no change. Car has a very slight hesitation at slow speeds which I know is related. Checked possible causes for this code and one was fuel pressure so I replaced fuel pump and filter. Car has 150k miles so I figured it was tired. Still getting the 02 sensor slow to respond. Please help ,I’m stumped. Any comments will be greatly appreciated.

Ivan, great video and info!!!!!!!

My 2000 4 cyl Camry, fixed this code by replacing the VSV on back of engine, it's connected by vacuum hoses to the EGR and modulator the VSV sticks briefly during the emissions quick self test, works ok otherwise and will test ok.

Way to go again Ivan. You're the man. Have you ever thought about being a master certified Toyota technician?

Wow, they stuck with an _old_ design! This is the same EGR system design as was on my 1986 Nissan 720. The "EGR vacuum modulator" here was called the "backpressure transducer (BPT)" on that truck, and the VSV was a wax thermostatic valve, rather than an electronic solenoid. All the Japanese truck designs of that era were the same, so who knows who created it, but it's interesting to see that they didn't change much over all those years.

Now we want to see a timing belt and a two leak oil job... and a water pump replacement... need good cooling when going to Texas... :-)

Hey Great Video thank you! The sound that the timing belt was making is the same symptom my Rav4 97 has, after installing a new belt! did I miss something? Spring tensioner? what fixed it?

Great work Ivan you are the man thank u for sharing.. If I may ask where did you get that vacuum gauge pump? We have them here in Memphis at that auto parts stores but they are all made of plastic not sure of the compatibility between the two but yours looks more durable I'm looking to invest in one to add to my small arsenal of tools but I need to invest smart on something that is going to last do u think that the plastic ones worth are it or should I keep looking.. Preferably the one that u used in the video.. Thanks brother God Bless

Hi my friend you did the best you could do to find the egr problem switch

Just had this issue on a 99 at the shop the other day. I feel for you having to get to that thing with out a lift! Cause it was hard enough to get to it when mine was on the lift!

Your video are always well done Thank You Bill N

Another great video 👍

Merry Christmas and a Happy and Healthy (healthier) 2019!

Kinda backwards system when it comes to control, but in all my yrs, only replaced 1 VSV. Most times I've found the pressure modulator ( transducer similar to what Chrysler used back in the day ) sticks or has weak diaphragms. . Also have found on really high mileage cars, the TB was coked enough to where the vac signals weren't strong enough to lift the valve. I think those older Toyopets look at o2 data and maybe some MAP to see if the EGR is flowing as desired or not. As you stated, the older OBD2 cars are somewhat dumb, and they didn't think it relevant to check electrical control yet. The transducer is critical for proper function. If you experience a stumble or surging at tip in or cruise, look there. And you'll never see a code, because it happens so fast that the ECM adds a bit of fuel, still within short term limits, to compensate. Because this system is 90% vac/mechanical, there's alot of variables.

Merry Christmas Ivan

A great many of these videos with a p0401 end up being that vsv solenoid on the backside of the engine by the firewall. How much work do you think it would be to relocate that valve to the top of the engine?

You are brilliant! Thanks!

Ivan, Great video and explanation of the EGR system. I love learning about this stuff. Let us know if you get to do any of the work you are recommending. I fear that the owner may not want to put that much $$ into an 18 year old car. God bless Paul

I say forget about the EGR and fix the belt and leaks - that's what I'd do if it were mine. 😉 Surprised Toyota had that complex of an EGR system that long ago. Lots can fail there. Remember the days when the Japanese used to design vehicles with as few ways to fail as possible? Sure do wish I could go back to that time. I think the old bosses from those days would've fired whoever mounted the VSV waaaaay under there too! I swear they're trying to be like domestics ... If we don't see you until after, you and your family have a Merry Christmas, and a Happy, Prosperous New Year, Ivan! 🍻

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 should you decide to take out the entire EGR assembly

hey Ivan! i have a 1998 toyota camry 2.2l as well, it only has a 103,000 miles on it, and this code popped up as well, p0401. So went ahead and just replaced the egr vsv solenoid(with a genuine part), the egr valve and as well as the modulator. I then cleared the code, went on a road test and after 2 trips, the light came back on with the same code, p0401. any tips and ideas?

I just replace the modulator and the valve I have not reset the battery. should the check engine light come off by itself if either of those were the issue?

great as always , and a Merry Christmas to you and your family .

Well, i replaced my egr valve, modulator and vsv switch but i still get the p0401 code ? Any clue on it ?

Thank you for a great video!!!!

Hi there ,if egr is open all the time , that would kill the engine at idle , and how long would this diagnostic take without filming ? thank you

I just replaced my egr valve per recommendation of my mechanic. Car is still rough idling after I erase codes (was fine before I erased the codes!) Should I move to replace the modulator? I don't have a lift so after that I'd have to hand it over to a mechanic.

I have a 1997 V6 Camry. Do you have a video for that or know of a good one?

So I shouldn’t sweat it if check engine light just went on? Any gasket replacement? Gonna trouble shoot and check clogs, what can I clean part with? Reply ASAP please.

Min 26:47 EXACTLY what I always say! Hondas and Toyotas are great (and my fav) but you gotta take care of them too!

The VSV only serves to cut off the EGR valve at deceleration and as additional protection to prevent the engine stalling at idle, but the 4-cyl Camry engine can idle fine even if the VSV is stuck open. That means that the EGR valve is closed at idle even with a stuck VSV and prevents a stall. Here's why. The VSV is fed by the modulator port Q which brings ported vacuum (not manifold vacuum) at port P through the modulator. At idle, there is zero ported vacuum at port P and so also at port Q. That's what keeps the EGR valve closed at idle regardless of the VSV. As the engine rpm increases under load, ported vacuum builds at port P which then flows through to port R and opens the EGR valve. (details of the modulator port R and exhaust backpressure are not relevant to this discussion) On the V6 1MZ-FE, the default is for the VSV to be closed (reverse of the logic of the 4-cyl) blocking vacuum from a constant vacuum source VCV, so there's a possibility of the engine stalling if the VSV is stuck open. Fortunately, EGR VSV failures are rare on a V6. Much more common on a 4-cyl.

Awesome job!

Great diagnostic

Had the same code recently. A couple of blows with the BFH on the EGR base and flow was restored.

Question for you? I just took my car to AutoZone and used there OBD2 scanner and the print out came up with the P0420 code and it said below threshold for catalytic converter and the print out said the Map sensor is bad. The car will run fine for 20-30 mins. Then cough and loose power and sometimes shut off. Could this be a EGR valve too? This emission stuff is crap. eBay has a used but guaranteed factory Map sensor on line. Mine looks like somebody kept it together with cable ties. And a degreased the engine with gunk because oil was everywhere from a leaking valve cover gasket and oring seals. That's fixed. I might of got water by mistake on the map sensor. It also had duct tape on it. Nice job!! By previous owner. I also bought NGK PLUGS that are platinum instead of iridium ones like denso. I replaced the fuel filter that was not fun. Any ideas that I should be doing or not be doing! Thank you David

Nicky done Ivan! You just couldn't help yourself 🤣

Before you opened it I kept saying to myself...he's going to open it 😅. Wow she needs a complete timing job on that thing,forget about the egr lol .

Thank you I appreciate your help

The 4 cyl sets P0401 by measuring the MAP. If that's higher than what the ECM expects (when exhaust is flowing with the VSV closed), it will throw an P0401. The stall test initial diagnosis is valid here too.

Hi there, I want to know if my Toyota Camry 2011 2.5L a Dynamic Force Engine ?

Great channel.

Classic vid I got the same car with the same code n no symptoms long term fuel trim set at 24% at idle only!!!

Great video thanks bud

I got a 1997 Toyota Corolla it will run sometimes and sometimes it won't I put a new relay fuse in it and it's still doing the same thing I need help on fixing the problem

Welcome to Texas!

Whr r u located ivan? I have two toyotas with problems one is a 1997 toyota celica and a 1993 toyota supra

Totally agreed, care and maintenance car owners. Don't put off maintenance and fix things that go bad as soon as possible. Even in the old days, if the horse you are riding requires a new horseshoe, don't delay or the horse will be lame. On this Camry, it looks like it will need a steam cleaning underneath first, what a nasty mess it is.

Well done diagnostics. Those engines were bad for valve cover gaskets leaking as well.

My check engine lights been on I changed the egr valve check engine light was off for about a month but when I got on the free way it came back on again

Ivan. I have a 97 that had a similar issue. It’s a bear to get that VSV out as you discovered. It is in the worst place. A notorious oil leak location is behind the coil pack mount. There is a plug there which is very difficult to see. It is where a distributor would have been located. It always drips in the location you showed and on the top of the transmission case where it pools. A big mess. Not to plug myself, but I have a few videos on my channel about this vintage Toyota engine.

Have a 98 that I've had the same light for 2 years that I'll be doing after the holidays. 156kmiles. Bought it for $1600 cash back 7 yrs ago with 151k miles on it. Sat pretty much for the last year and half until this fall when I sold it for $2500... part of the deal was to fix the code. I'll let you fix it for me and my job will go really fast. OF the first 10min I watched is what I've read about so far using suretrack as well. Are you using Alldata or the DIY version since it's a regular customer?

Same code on my 2001 camry. Changed all 3 parts (egr valve, regulator and VSV switch) check engine light still on same error code. Stuck on this

Dude awesome mine had the same problem.

Superb bro

So, where was the oil coming from? I'm expecting the vac hoses/egr system on my 99 Camry to start sucking air soon. The gas cap already gave me a scare, but it was just the seal. I'm just gonna buy all the OEM EGR parts over the winter and replace it all in the spring. I wanna keep this car forever!

Great video..

Hi there. When you have a good VSV and you test it with the multimeter what should be the ohms reading. ( numbers) Thanks. PS Great video 👍🏻

Nice vid Ivan,how about a Pt.2?

Weird, that is very similar to the early 90s Suzuki Sidekick/Samurai systems. They only had one ported vacuum reference. That system was designed by Mitsubishi IIRC.

Could you give me the website your using on your computer? All I can make out is ‘ alldata”

You have to tension the timing belt correctly to make sure it doesn’t do that again. You gotta hold up the tensioner pulley and tighten the 14 mm tensioner pulley bolt to get it right. The tensioner pulley spring is NOT enough tension on that belt by itself. This will avoid a comeback for improper belt tension and it could make noise if you don’t do the procedure I explained.

These little VSV valves can be easily relocated to a location up higher on the fire wall near the intake manifold. No wire or vacuum line cutting required. Makes it easier for the next guy (and testing). Just look for an available stud bolt to hold the VSV valve. The vacuum lines and electrical connector can be pulled up through the intake manifold. Be mindful of the clip securing the wiring loom to the block.

great job

Is all of this really important and necessary? Or just market?

I'll say, plugged/carboned EGR ports, the other troublesome area is the vacuum hoses and steel lines/nipple... they've always been troublesome since the first EGR installed and the 22R loved to rust and plug the steel lines and nipples, often loosing vacuum to the dual-pot advance and not modulating the egr flow, causing a massive cruise and tip-in stumble/near stall out >_>

Thank you Ivan. Good job. Any ideas on why they needed two vacuum supply hoses from throttle body to the vacuum modulator? Also, just for clarity. Is the EGR valve Off equals the VSV energized On to open it's vent port? And then, EGR valve On equals the VSV de-energized Off to close its vent port?

How did you remove it?

When I saw the title, I said "VSV!" Been there, done that. I went through the RF wheel well. Invented a few 4 letter words, wished I had 4 elbows and hands the size of a Toddler. Why did they put it there? Because Toyota.

great video. thax

Nice video Ivan, second video on Toyota EGR system in 2 days to pop up in my feed. Just wondering if you have watched any of the WeberAuto channels videos. Very detailed videos. I was reading about the guy and it looks like he developed and owns a vibration analysis software company used by GM and Ford. Just thought it was interesting, if I remember correctly you are working the the vibration analysis field now as well.

Good video ...

How is still in time with all that slack???

I have Toyota highlander 2006 v6 3.0 the engine is on, some time flashing but some time not flashing