P0401 Code $656 and counting... - Toyota Nation Forum : Toyota Car and Truck Forums

pfinn · 01-03-2010, 08:03 PM

Looking for some help...2000 Toyota Camry 4 cylinder...independent garage has done the following:
1. Replaced EGR Valve
2. Replaced VSV Control Module
3. Replaced 2 VSV Control Module hoses
4. Replaced Reserve Tank Assembly
Still getting a Check Engine Light P0401 Code. It seems like the garage is replacing parts until they get it right...what would be the next step? Don't want to go back to the same garage...Thanks!!!

Chris Crash · 01-03-2010, 08:07 PM

Well your first mistake was letting a garage throw parts at it.

But P0401 means insufficient flow. So. Somewhere along your EGR/VSV line, you've either got a leak, a block or a partial block.

Was the tube going to the EGR valve replaced or at least inspected?

pfinn · 01-03-2010, 09:20 PM

Thanks Chris...I agree. The car is actually my sisters. I was reviewing her invoices trying to help her using the resources of this forum. I can't tell by her invoices if the tube to the EGR was replaced or inspected. The shop charged a $75 diagnostic fee each time the car was brought in. They read the codes...but I believe they don't use proper testing procedures...just keep replacing parts. What is the best way to test for a block? I am new to DIY...

Chris Crash · 01-03-2010, 09:41 PM

The only way would be to disassemble it and check to make sure air flows through it properly.

Sometimes you can get away just with cleaning the valve and tube instead of expensively replacing them.

I wouldn't stress the issue TOO much because the EGR valve is a non-essential part of your car. Yes, it is for emissions and they will probably rape you about it in California. But the car will still run just fine without it.

P.S.-Don't go to that shop again.

ShawnM · 01-03-2010, 10:14 PM

Easiest way to check for or rule out a blockage is to pull a vacuum on the small fitting on top of the EGR valve while the engine is at an idle. If it starts running really bad or dies out then there is no blockage. Of course any competent shop would have checked that first. If the code was the same everytime you went back then I would raise hell about the repeated diagnotsic charge. You should only be charged once to diagnose or fix 1 problem. I shure wouldnt call what they are doing diagnosis. More like reading codes and throwing parts at it.

finfinder · 01-03-2010, 11:30 PM

what about the EGR modulator ?

haux · 01-04-2010, 12:14 AM

P0401 was coming up for me for quite some time, until recently I finally decided to fix it. I replaced the EGR valve, EGR pipe, EGR modulator, along with every vacuum hose I had easy access to in the engine bay. The code has not come back up, but a diagnostic was done and P0401 showed up as pending. So it's sort of on the verge of coming back. I have a new VSV for the EGR but have been unable to replace it myself after two tries. I expect that after it's replacement, the code will be eliminated for good.

I would perform whatever testing was recommended in the previous post to check for blockage. The vacuum hoses you can see are extremely easy to replace if you feel like doing those. The EGR pipe obviously has no moving parts... so it can't fail in THAT way. But if it's blocked with carbon buildup, or rusted with holes... then it may possibly be a cause.

From your list, it looks like the EGR modulator was not replaced. It is fairly inexpensive from the dealer, and the only things holding it in place are a metal clamp and the hose attached to the bottom of it. Can be replaced in two minutes.

Chris Crash · 01-04-2010, 12:54 AM

Quote:

Originally Posted by haux

P0401 was coming up for me for quite some time, until recently I finally decided to fix it. I replaced the EGR valve, EGR pipe, EGR modulator, along with every vacuum hose I had easy access to in the engine bay. The code has not come back up, but a diagnostic was done and P0401 showed up as pending. So it's sort of on the verge of coming back. I have a new VSV for the EGR but have been unable to replace it myself after two tries. I expect that after it's replacement, the code will be eliminated for good.

I would perform whatever testing was recommended in the previous post to check for blockage. The vacuum hoses you can see are extremely easy to replace if you feel like doing those. The EGR pipe obviously has no moving parts... so it can't fail in THAT way. But if it's blocked with carbon buildup, or rusted with holes... then it may possibly be a cause.

From your list, it looks like the EGR modulator was not replaced. It is fairly inexpensive from the dealer, and the only things holding it in place are a metal clamp and the hose attached to the bottom of it. Can be replaced in two minutes.

Not to sound harsh, but how are you unable to replace the VSV?

haux · 01-04-2010, 03:36 PM

Quote:

Originally Posted by Chris Crash

Not to sound harsh, but how are you unable to replace the VSV?

The reach isn't one of the easiest. I couldn't get to it lying under the car because of the halfshaft and the big bracket holding it. From the wheel well, I just couldn't get it unscrewed. No room for a larger socket wrench to turn, and the smaller ones were too weak.

I suppose if I had a car lift... standing under it would be a tad easier.

hill8570 · 01-04-2010, 04:36 PM

Any other codes? A funky MAP sensor can also cause a P0401. Normally, you'd see a P0105 or P0106 at the same time, 'tho.

Chris Crash · 01-04-2010, 04:46 PM

Quote:

Originally Posted by haux

The reach isn't one of the easiest. I couldn't get to it lying under the car because of the halfshaft and the big bracket holding it. From the wheel well, I just couldn't get it unscrewed. No room for a larger socket wrench to turn, and the smaller ones were too weak.

I suppose if I had a car lift... standing under it would be a tad easier.

When I changed mine, I just put the car on those drive on ramps you can buy at WalMart. Crawled under and used a socket wrench.

I don't remember having trouble reaching it or loosening it, It was hard to get the vacuum lines off though!

I used a 1/4" drive socket wrench, btw.

***JohnGD*** · 01-04-2010, 07:34 PM

Use a free loaner tool MityVac from Autozone to measure the vacuum at the throttle body ports connected to by the modulator. You should see engine vacuum at those ports as you open the throttle past them. Dirty ports can stop EGR from opening, because it's not giving off the right signals.

A stepper motor controlled "digital EGR" systems would be better. The ECU already has all the info it needs. But then again, these engines are ancient.

Also, you can measure the vacuum at the EGR valve when the engine is at operating temperature and it 2500 rpm. What do you read?

Quote:

Originally Posted by pfinn

Looking for some help...2000 Toyota Camry 4 cylinder...independent garage has done the following:
1. Replaced EGR Valve
2. Replaced VSV Control Module
3. Replaced 2 VSV Control Module hoses
4. Replaced Reserve Tank Assembly
Still getting a Check Engine Light P0401 Code. It seems like the garage is replacing parts until they get it right...what would be the next step? Don't want to go back to the same garage...Thanks!!!

j2b4osan · 01-06-2010, 06:40 AM

my friend has this code popping up as well as a random cylinder misfire. the car has no power feels like its limping. could he misfire be related to the egr?

haux · 01-06-2010, 07:51 AM

Quote:

Originally Posted by j2b4osan

my friend has this code popping up as well as a random cylinder misfire. the car has no power feels like its limping. could he misfire be related to the egr?

I would say misfires are most commonly because of a bad spark plug or two.