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g450 - Fault code P0471 - Exhaust pressure sensor

21K views 13 replies 4 participants last post by  SaVAGeSoot  
#1 ·
Quick question for the brains trust. Does the narrow tube on sensor part number 059 906 051A only have a short hose attached that leads nowhere or did I break something off? If its a nothing hose, what pressure difference is it meant to measure? I thought it was supposed to measure before and after DPF hence 2 holes.

Car: 2008 CASA 3.0 v6 tdi @ 113k km

I got this fault and a couple related faults that cleared but P0471 always remained. Drove the car a few more days but always had to clear fault codes every drive coz of annoying alarm going off every 3 sec like the world was coming to an end. Thank goodness for $7 AUD bluetooth OBDII adapter and Torque Lite app. I had a good idea it was the sensor so replaced it today and all looks good. No more CEL alarms/faults.

BTW-$120 AUD from stealer coz CBF hunting around all day on phone for one. Repco never had them on the books nor Bursons.
 
#2 ·
BTW- above part and pic replaces old part 07Z 906 501B which when measuring resistance across the three terminal had an open circuit across 2 out of 3 and high resistance across another 2 of 3. The new one had lower resistance across all three terminals no matter how you connected ohm meter. Hope this helps someone.
 
#4 ·
The smaller diameter barb fitting on the pressure sensor only has a 4" long piece of tube fitted the other end is open to the atmosphere.
The larger barb of course is fitted with the hose that runs down to the engine side of the DPF filter
You are not missing any thing the CASA engine only has one outlet on the DPF filter closest to the engine. (176 kw engine)
The BKS engine (165 kw engine) has two lines that run to the DPF on each end or before and after.


I had this issue a week ago when I replaced a G450 sensor and thought I had broken it also during removal but some investigation showed there is no 2nd line on the CASA engine.


regards
Drag
 
#6 ·
Sam ( If I may call you that)
I have fitted 2 x G450 sensors over the last 3 weeks to vehicles having a DPF sensor fault.
One of them also had pre DPF temperature sensor fault with disappeared when replaced but the G450 fault remained.
As above engines were a
- BKS with 220,000km both sensors G450 and temp showing faults and when replaced all faults cleared and have not returned to date.
- CASA with 275,000km G450 replacement cleared fault and it also has not returned.


One thing to be observant of I believe is the pre DPF mbar reading the G450 displays after replacement just to also give a gauge to how much your DPF is restricted.
I did some logging on pressure and also got some logged info from Hedditch (thank you) from a car with no issues and similar kms.
I can now reasonably see how much restriction should be seen in a working but not new DPF.
- at idle about 7- 12 mbar (1 mbar is 0.014 psi)
- rev car while standing still with no load 100- 120 mbar
- at cruise (80 km not a lot of load 80 m-100 mbar.
- WOT full boost at about 80 kph anything up to 400 mbar (that's nearly 6 psi back pressure and I would think be getting up toward max you would want but that's a guess)


All these above were from cars with no faults but over 200,000 kms on the clock.


Did you also adapt the new G450 sensor after fitting? i.e. tell the car you had fitted a new sensor ?
I did and it changes you DPF loading to what I would think the ECU calculates from the parameters it has in its settings as the old sensor may have not been accurate..


regards
Drag
 
#7 ·
Good info there Drag. I think I adapted sensor by doing the below. Wasn't confident on doing it with VCDS.

-Ignition ON
-Wait 5 seconds
-Ignition OFF
-Wait 40 seconds
-Repeat 4 more times

I took some VCDS readings. Tell me if it looks right coz readings are zero where before they had something.

First pic is at idle and the rest at revs whilst stationary in park. MVB104.4 was showing 980km before I tried a DPF regen that failed after 10min.

Regards
Sam. Yes u can call me that or stupid depending if I've done this right. I've read an ex long time VW mechanic just put new sensor in without adaptation.

Image
Image
Image
 
#8 ·
Sam
I am fairly sure that turning the ignition on and off will not adapt the sensor but there is a specific command in the VCDS adaptations that does !


What adapting the sensor does I believe is allow the ECU to see how much your DPF is really loaded and that's why your MVB 104.3 on all 3 screen shots is showing actual as 0.0


I presume that you car has some kms on the current DPF so I am sure it has more content than zero !


I think if you adapt it (G450) via VCDS it will show you and the ECU the correct loading of the DPF and that will be more than 0.0.
If you have no faults it should run a service regen if you ask it to via VCDS.


regards
Drag
 
#9 ·
Is this how you adapt drag? I couldn't find anything specific on touareg:

CAN Protocol (G450) procedure

Instructions should be populated in a pop-up balloon when connected to the controller in question with VCDS.

Key ON, Engine OFF
[Coding-2]*or [Login-II]*button
Enter the code shown in the VCDS pop-up balloon
[Do It!]
Switch Ignition OFF for 30 seconds
 
#10 ·
Is this how you adapt drag? I couldn't find anything specific on touareg:

CAN Protocol (G450) procedure

Instructions should be populated in a pop-up balloon when connected to the controller in question with VCDS.

Key ON, Engine OFF
[Coding-2]*or [Login-II]*button
Enter the code shown in the VCDS pop-up balloon
[Do It!]
Switch Ignition OFF for 30 seconds

Are those instructions taken from the Rosstech site ?
If so they may sound correct or suitable but it is not quite how it works from the computer


- You need to be in Engine module of course.
- I think its the adaptation -10 tab on the RHS of the screen.
- Having a look at the drop down box line that appears it has a selection to adapt new DPF pressure sensor or something like that.
- When you find the right one you will get a pop up with instructions.
- Basically you add 0001 in the new value box,
- Click the test tab.
- Then click the save tab.
- Then cycle off the ignition for a good 10 seconds but I leave for at least 20 secs.
- Turn it back on and check the MVB in 100, 102, 104 and see what changed and if I am correct your 104.3 will have changed and possibly 102.3


regards
Drag
 
#11 ·
Cheers Drag.

Are those instructions taken from the Rosstech site ?

Yes but for a 2.0 CR TDI.

I found mine in Long Adaptation and entered 0001 but there do not appear to be any changes from my alternative adaptation method. I've put on 100 odd km since new sensor and figures at 104.2 and 104.3 seem to be growing steadily. I did notice 104.2 did get down to zero after a 10min failed regen on the old sensor.

If anyone here has VCDS and approximately 113k km on dash can you please post your 100,103,104 figures.
Sam
 
#12 ·
Ok. So here is some snaps of VCDS after a 90km freeway drive(1hr) taken the next day straight after a cold startup.
Image


This one is immediately after the return trip.
Image


The only thing that concerns me in all these pics is the static number at MVB102.2. The km since regen 104.4 seems to make sense after a long trip. No?
 
#13 ·
Sam ( If I may call you that) I have fitted 2 x G450 sensors over the last 3 weeks to vehicles having a DPF sensor fault. One of them also had pre DPF temperature sensor fault with disappeared when replaced but the G450 fault remained. As above engines were a - BKS with 220,000km both sensors G450 and temp showing faults and when replaced all faults cleared and have not returned to date. - CASA with 275,000km G450 replacement cleared fault and it also has not returned. One thing to be observant of I believe is the pre DPF mbar reading the G450 displays after replacement just to also give a gauge to how much your DPF is restricted. I did some logging on pressure and also got some logged info from Hedditch (thank you) from a car with no issues and similar kms. I can now reasonably see how much restriction should be seen in a working but not new DPF. - at idle about 7- 12 mbar (1 mbar is 0.014 psi) - rev car while standing still with no load 100- 120 mbar - at cruise (80 km not a lot of load 80 m-100 mbar. - WOT full boost at about 80 kph anything up to 400 mbar (that's nearly 6 psi back pressure and I would think be getting up toward max you would want but that's a guess) All these above were from cars with no faults but over 200,000 kms on the clock. Did you also adapt the new G450 sensor after fitting? i.e. tell the car you had fitted a new sensor ? I did and it changes you DPF loading to what I would think the ECU calculates from the parameters it has in its settings as the old sensor may have not been accurate.. regards Drag
Hello, Is it possible to changed a faulty G450 sensor with our removing the engine and gearbox, which is what my dealership is telling me? This is on a 2007 Touareg V10 TDI with 64,000 miles. Many thanks, David