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Old 11-03-2004, 12:17 PM   #1 (permalink)
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Fixing EGR Code P0401

Can anyone help? Engine light on nonstop. Car runs fine. I've been to two mechanics..spent $200. Toyota dealer says prob is P0401, and suggests new vacuum switch valve (says that may not fix prob but wants $300 more to replace). However, on diagnostic test it says "VSV and EGR valves are working" -- I don't know where to go..but I need to complete registration. Any ideas? Larra http://www.toyotanation.com/forum/im...cons/icon9.gif
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Old 11-03-2004, 03:10 PM   #2 (permalink)
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Re: Fixing EGR Code P0401

Quote:
Originally posted by quigley
I've been to two mechanics..spent $200.
What did u spend those $200 dollars on?

I got the similar prob and the car been running fine since the summer. Went to autozone for that general diagnostic and they say its the PURGE valve thats messed up... (Yea, been driving with the light on since like early July-BUt, car still great)

I don't have the money to do the repairs yet....
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Old 11-03-2004, 08:32 PM   #3 (permalink)
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According to Toyota's schematics that another member graciously sent me, the trouble areas maybe;

EGR valve stuck closed.
EGR Vacuum Switching Valve (VSV).
EGR VSV open circuit.
EGR valve position sensor open or short circuit.
EGR valve position sensor.
ECM.

I could email you a copy if you want, but it's mechanic gibberish.

I had a P0401 before and it turned out to be a spliced vacuum line. Hopefully you'll be as lucky as I was.
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Old 11-04-2004, 05:46 PM   #4 (permalink)
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I spent the money on diagnostics and resets. AutoZone can't give the free tests in our area any more--pressure from the mechanics union or some such thing. It is a valve problem for sure. I talked to a mechanic who sounded much more knowledgeable than Marin Toyota..who seemed nice but clueless. Evidentally, it has to be test driven a special way after repair, to see if the fix sticks. Bummer, but we are in an "enhanced" smog zone here--just have to bite the bullet, I guess. Thanks for your help, fellas. I think they see me comin' a mile away!
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Old 11-04-2004, 09:03 PM   #5 (permalink)
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It would be a good start, letting us know what kind of car and engine it is.
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Old 11-05-2004, 10:58 AM   #6 (permalink)
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Of course. Sorry. It is a Toyota Rav 4 - 1998, 4 whl drive. It has 72K miles on it and it is manual shift (Must be a 4-cylinder, I guess).
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Old 11-05-2004, 01:20 PM   #7 (permalink)
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replace the vsv on the back of the head.
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Old 11-05-2004, 03:28 PM   #8 (permalink)
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Thank you DeeKay140...you sound pretty certain. Actually, that is what the Toyota guy said, but, he said, he could not be sure that was it (he sounded VERY equivocal)...and it would cost about $96 for the part and $180 labor to find out. Plus he didn't mention the test drive--(the other mechanic said I could not do the test drive properly and he had to do it). Does this make sense to you? Do you think I should just go ahead with it then? Quig.
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Old 11-05-2004, 05:32 PM   #9 (permalink)
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the problem is usually intermittent, that is also a 2 trip detection trouble code.( meaning the car has to see a certain set of bad values on 2 seperate key cycles) The part is about 80-95 dollars at toyota, its an ez repair,but hard to get to. its even tougher on the rav 4x4

I am a toyota master tech. so I am giving u sound advice. The vsv is the most common problem. if the egr itself was sticking, the car would stumble or die on decel.

The problem is , when u remove the part and test it, it sometimes tests ok. so its kinda of a educated guess by process of elimination.

If the part was bad all the time. u could clear the codes by disconnecting the battery. then drive it for a day and it should come on fairly quickly.. you drive the car up to 50 mph or so. stop, turn the car off, restart it and do it again. if the part was shorted, the chk eng light should come back right away..


good luck and keep us posted.
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Old 11-05-2004, 06:57 PM   #10 (permalink)
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Well, thank you! It is so nice to get sage advice from an expert! I'll try the disconnect battery thing this weekend.
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Old 08-10-2005, 07:36 PM   #11 (permalink)
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EGR Check Engine Code and 1998 Toyota Camry

I have the same problem -- the check engine code has been on nonstop but the car was running fine. I had the oil changed, and brake pads replaced and had them pull the code -- mechanic said that it was 1 single code for EGR -- could be something simple or not. He cleared the code and told me that he wouldn't really affect anything except my emissions (my car passed the NOVA/DC emissions test this year). The check engine light came back on again after about 20 miles -- should I have him look into it further? please help. --

Oh -- it is a 1998 Toyota Camry Automatic 4 Cyl. with approx 50k miles on it.

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Old 08-10-2005, 09:18 PM   #12 (permalink)
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replace the vsv as stated in this post.
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Old 08-13-2005, 11:56 PM   #13 (permalink)
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yeah replace the egr vsv, lots of problems with those. to make absolutely suer the diag steps are as follows. start the engine, connect a hand held vacuum pump to the rubber hose coming off the egr valve, apply vacuum to it if it tries to kill the engine, the egr valve itself is working properly, (it adds spent exhaust gases to the incoming air charge therefore reducing the temperature of the combustion chamber during combustion, lowering the production of harmfull gases).... next see if the intake is sending enough vacuum to the vsv to operate the egr valve, this is done by connecting a vacuum gauge to the modulator ( a round plastic with a red metal top with 3 ports coming out of the sides, loctaed on the top of the intake manifold next to the throttle body) connect the gauge to the Q port and open the throttle to approximatly 3000 rpm, the guage should read around 20 inches of vacuum, if it doesnt check the vacuum hoses that connect to the front of the throttle body if the are good replace the modulator, if it does pull 20 inches check the lines that go to the vsv, if they check ok then by the process of elimination, the vsv ( vacuum switching valve, which opens when told to do so by the ecm providing vacuum to the egr) has to be the problem.

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Old 08-17-2006, 01:10 AM   #14 (permalink)
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Quote:
Originally Posted by toyo_tech02
yeah replace the egr vsv, lots of problems with those. to make absolutely suer the diag steps are as follows. start the engine, connect a hand held vacuum pump to the rubber hose coming off the egr valve, apply vacuum to it if it tries to kill the engine, the egr valve itself is working properly, (it adds spent exhaust gases to the incoming air charge therefore reducing the temperature of the combustion chamber during combustion, lowering the production of harmfull gases).... next see if the intake is sending enough vacuum to the vsv to operate the egr valve, this is done by connecting a vacuum gauge to the modulator ( a round plastic with a red metal top with 3 ports coming out of the sides, loctaed on the top of the intake manifold next to the throttle body) connect the gauge to the Q port and open the throttle to approximatly 3000 rpm, the guage should read around 20 inches of vacuum, if it doesnt check the vacuum hoses that connect to the front of the throttle body if the are good replace the modulator, if it does pull 20 inches check the lines that go to the vsv, if they check ok then by the process of elimination, the vsv ( vacuum switching valve, which opens when told to do so by the ecm providing vacuum to the egr) has to be the problem.
Awesome response!! A++!!
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Old 02-18-2007, 05:32 PM   #15 (permalink)
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Toyo_Tech and Deekay:

I am a newbie 99 4runner 2wd 2.7 owner. Just bought the car and got CEL the next day. I am getting a p0402 code which is Excessive EGR flow. Could the vsv and modulator cause this code as well as the p0401?

Thanks,
Stan Henley

Last edited by Henhouse1; 02-18-2007 at 05:34 PM.
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