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Volkswagen OBD II 97 Eurovan with P0400 EGR Flow Malfunction


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Last Post: Jul 6, 2014 3:22 PM Last Post By: winmutt
vw-eurovan

Posts: 52
Registered: 12/18/06
97 Eurovan with P0400 EGR Flow Malfunction
Posted: May 27, 2007 8:22 PM
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Back in January I posted on the 92-03 Eurovan forum "IM Monitors Not Ready" about an EGR problem that I had with my 97 EV. Following all the troubleshooting, I went to the local emissions inspection center and passed.

I didn't drive the vehicle much, but just a couple of weeks ago the check engine light came on again and it had the same OBD code, P0400. I went back and checked for vacuum to the solenoid at idle, voltage to the solenoid at about 3000rpm (with a DMM), and a small amount of vacuum at the EGR valve itself at 3000rpm. I applied vacuum to the EGR valve with a hand pump at idle and the engine stalled. Everything seemed ok, but the fault comes back after it is cleared and the vehicle is driven.

My engine scanner does not read the EGR temp sensor, so I can't run the test in the Bently manual. Does anyone have any ideas on what I can look at next?

I wish I could monitor the EGR Temp sensor resistance with the vehicle running, but I don't know the thermistor temp-resistance properties.
Port Fellamay

Posts: 4,105
Registered: 01/18/04
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: May 27, 2007 10:05 PM   in response to: vw-eurovan in response to: vw-eurovan
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try to clean the egr valve, it tends to get gunky and stick.
vw-eurovan

Posts: 52
Registered: 12/18/06
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: May 27, 2007 11:07 PM   in response to: Port Fellamay in response to: Port Fellamay
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I tried that already. Now it appears to move linearly with the vacuum I apply using a hand pump. When I re-assembled it, I still got the fault.

Any other suggestions?
vw-eurovan

Posts: 52
Registered: 12/18/06
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: May 28, 2007 9:27 PM   in response to: vw-eurovan in response to: vw-eurovan
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Attachment EGR Solenoid.jpg (310.5 KB)
I found another posting in the Audi forum where someone applied an external voltage to the EGR solenoid with the car idling. I thought this sounded like a good idea, so I tried it. I disconnected the vacuum line to the EGR valve and connected it to a vaccum gauge. I also connected a gauge to the hose going to the intake manifold. I applied 12V to the solenoid with an external source.

What I found was 16inches of vaccum on the EGR intake and only 8 on the outlet when voltage was applied. There valve was completely closed with no voltage applied.

Is this OK or not? I don't want to buy a new valve without knowing that this is a problem.
vw-eurovan

Posts: 52
Registered: 12/18/06
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: May 31, 2007 9:15 PM   in response to: vw-eurovan in response to: vw-eurovan
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I have learned from a VR6 article that 8in (-270mbar) of vacuum is not unreasonable for the vacuum on the EGR valve when the solenoid is fully open. It should be about -200mBar. Now I suspect the EGR temperature sensor.

I measure 150kOhm at about 28C. Can anyone tell me what the resistance-temperature characteristic is for this sensor? The Bently manual shows the characteristic curve for other sensors, but not this one.
zig39

Posts: 1
Registered: 07/15/19
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: Nov 11, 2007 2:14 PM   in response to: vw-eurovan in response to: vw-eurovan
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I have a 2000 Eurovan and had same issues. EGR valve tested good, temperature sender checked out ok. I then went to the combi valve which has a vacuum line to the air pump. This line was cracked and had a leak. I replacd that line and so far the MIL light and code have not come back.Sure hope this helps.
qval

Posts: 10
Registered: 02/12/08
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: Feb 12, 2008 2:31 PM   in response to: zig39 in response to: zig39
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Hi everyone,

I wanted to reply, saying I'd used the information on this message board to diagnose and fix my egr solenoid (frequency valve).

I was getting a p0400 and applied voltage to the solenoid.
It only clicked almost inaudibly, and a vacuum gauge confirmed that the vacuum on the source side of the solenoid was not getting to the egr valve side.

I took the solenoid apart (you have to break it a bit) and cleaned it up. Silicone sealant and a zip tie now hold it together and it clicks again!

Check engine light is gone!

Thanks. I'll post pictures if I figure out how.
qval

Posts: 10
Registered: 02/12/08
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: Mar 6, 2008 10:48 PM   in response to: qval in response to: qval
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By the way, the CEL is back on. I checked the fixed solenoid by applying 12 volts, and it clicked, but did not pas vacuum to the egr, so a new one is going in
qval

Posts: 10
Registered: 02/12/08
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: Mar 6, 2008 10:52 PM   in response to: qval in response to: qval
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By the way, the CEL is back on. I checked the fixed solenoid by applying 12 volts, and it clicked, but did not pas vacuum to the egr, so a new one is going in
b4tdi

Posts: 1
Registered: 05/20/08
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: May 20, 2008 8:17 AM   in response to: qval in response to: qval
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After fighting with the P0400 EGR Flow Malfunction error on my 99 EV off and on for over a year, I have finally resolved it, and passed the Mass. inspection in the process.

I had previously replaced all vacuum lines thinking a couple of marginal ones could be the problem, but it was a gunked up port on the throttle body that I believe was the cause. I removed the kombi-valve, rinsed its innards with a bit of carb cleaner, then carefully probed the small hole at the rear of the throttle body that the kombi-valve is bolted to. I found it to be very dirty and was able to pull out black gunk with q-tips soaked in carb cleaner. However, carefully probing deeper into the port with an awl, it appeared to be completely blocked.

There's probably a nicer way to clean the port (by removing the throttle body itself), but I just gently pushed through the constriction, cleared the code, drove for about 150 miles, and finally got all readiness zeroes (0000 0000).

Hope this helps someone.
winmutt

Posts: 2
Registered: 04/22/11
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: Apr 23, 2011 10:10 PM   in response to: b4tdi in response to: b4tdi
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My 00 eurovan had a blockage in the vac line from the EGR at the T where it pulls from the intake.
vwbillgin

Posts: 1
Registered: 01/27/11
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: Mar 24, 2014 9:22 AM   in response to: zig39 in response to: zig39
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Thank you for you 2000 Eurovan P0400 EGR Flow Malfunction post. My error only shows after a hot start, like when we stop for something and then get going again. I will learn about cleaning the EGR Valve, and the small hole in the Kombi Valve that is mentioned. But I am thinking the temp sensor is faulty.

Where is the sensor that you mention?

Thanks so much. Bill
winmutt

Posts: 2
Registered: 04/22/11
Re: 97 Eurovan with P0400 EGR Flow Malfunction
Posted: Jul 6, 2014 3:22 PM   in response to: winmutt in response to: winmutt
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Wish I had taken a picture of that T, code is tripping again.

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