Hi guys. I have C4 picasso 2007 1.6 HDI 109 EGS. I have a problem with the EGR. The EGR work but doesn't close when have to do it. When the car does regeneration the EGR is opened and come error P0234. I checked the EGR valve. It was clean and moved very smoothly and easy. Any idea where is the problem? When I use engine brake the EGR again is opened and the turbo pressure is high.
This is the link with the problem.
1.6 HDI EGR work but doesn't close
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Hell Razor5543
- (Donor 2023)
- Posts: 14260
- Joined: 01 Apr 2012, 09:47
- x 3275
Re: 1.6 HDI EGR work but doesn't close
Hi, and 
to the Forum.
I don't know if this advise will help, or send you down the wrong path, but if your EGR is actuated by a vacuum there will be an electrovalve to control this. It is possible (unlikely but possible) for such a valve to get stuck open, so when the ECU sends it the 'close' signal (or, rather, stops sending power to the valve to stay open) it remains in the open position, thereby keeping the EGR active.
to the Forum.I don't know if this advise will help, or send you down the wrong path, but if your EGR is actuated by a vacuum there will be an electrovalve to control this. It is possible (unlikely but possible) for such a valve to get stuck open, so when the ECU sends it the 'close' signal (or, rather, stops sending power to the valve to stay open) it remains in the open position, thereby keeping the EGR active.
James
ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
ex C5 2.0HDi VTR
ex C5 2.0HDi VTR
ex C5 2.2HDi VTX+
Yes, I am paranoid, but am I paranoid ENOUGH?
Out amongst the stars, looking for a world of my own!
ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
ex C5 2.0HDi VTR
ex C5 2.0HDi VTR
ex C5 2.2HDi VTX+
Yes, I am paranoid, but am I paranoid ENOUGH?
Out amongst the stars, looking for a world of my own!
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Ilich
- Posts: 3
- Joined: 30 Aug 2020, 12:55
Re: 1.6 HDI EGR work but doesn't close
Thanks for the answer but it is electronic EGR valve and the normal position is close. Without signal it must be closed.
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Rhothgar
- (Donor 2026)
- Posts: 2515
- Joined: 22 Nov 2004, 00:21
- x 226
Re: 1.6 HDI EGR work but doesn't close
That's a nice looking programme you are using there Ilich. What is it?
I am not familiar with modern turbo pressures but 2188mbar seems high.
I have a Saab 900 Turbo T16S Hooligan Edition in my collection and that runs at 1 bar (I assume that is 1 bar boost plus 1 bar normal atmospheric pressure but it is a BIG turbo with a lot of lag - exhaust from turbo is about 3.5" - 4" diameter!). Around 1993, Saab moved to LPT (Light Pressure Turbo) which chopped the boost pressure in half.
I am not familiar with C4 Picasso I'm afraid.
1) Have you or anyone else been doing any work on the engine recently?
2) Does the car enter limp home mode at any point?
3) Is the engine light on?
I imagine your car has a vacuum solenoid valve somewhere on the side or the rear of the engine with 3 pipes going to it, one pipe going to the EGR, on to the turbo wastegate and one to atmosphere.
If so, check the pipe to atmosphere is clear as without access to atmosphere the turbo may overboost.
If you have access to an oscilloscope, all solenoids that operate on a duty cycle produce a square waveform ~ 12V - 0V - 12V - 0V - 12V and so on ie ON / OFF / ON / OFF.
I'm unsure about this valve though insofar as it may only needs to operate at a certain rev band in which case you might not see it switching on and off at idle but only when you rev it and decelerate ie under certain conditions.
Maybe worth checking turbo wastegate actuator moves freely when engine is off too.
That's as much as I can tell you.
A photo of the EGR and any valve connected to it would be useful.
I am not familiar with modern turbo pressures but 2188mbar seems high.
I have a Saab 900 Turbo T16S Hooligan Edition in my collection and that runs at 1 bar (I assume that is 1 bar boost plus 1 bar normal atmospheric pressure but it is a BIG turbo with a lot of lag - exhaust from turbo is about 3.5" - 4" diameter!). Around 1993, Saab moved to LPT (Light Pressure Turbo) which chopped the boost pressure in half.
I am not familiar with C4 Picasso I'm afraid.
1) Have you or anyone else been doing any work on the engine recently?
2) Does the car enter limp home mode at any point?
3) Is the engine light on?
I imagine your car has a vacuum solenoid valve somewhere on the side or the rear of the engine with 3 pipes going to it, one pipe going to the EGR, on to the turbo wastegate and one to atmosphere.
If so, check the pipe to atmosphere is clear as without access to atmosphere the turbo may overboost.
If you have access to an oscilloscope, all solenoids that operate on a duty cycle produce a square waveform ~ 12V - 0V - 12V - 0V - 12V and so on ie ON / OFF / ON / OFF.
I'm unsure about this valve though insofar as it may only needs to operate at a certain rev band in which case you might not see it switching on and off at idle but only when you rev it and decelerate ie under certain conditions.
Maybe worth checking turbo wastegate actuator moves freely when engine is off too.
That's as much as I can tell you.
A photo of the EGR and any valve connected to it would be useful.
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Ilich
- Posts: 3
- Joined: 30 Aug 2020, 12:55
Re: 1.6 HDI EGR work but doesn't close
Hi. I have the car from 8 months. I don't know somebody to did any engine updates. When did regeneration or kick down the pedal the EGR froze opened and show me P0234 or P0100 or sometimes both of them . The EGR is electrical. I'm not sure is EGR problem or BSI. I don't know which module control the EGR. Maybe the problem is there.