# 3.0TDI problem, high fuel consumption



## tuut (Sep 13, 2016)

Hi fellow Phaeton drivers,

the engine check light has been on for a little while now, with fuel consumption higher than usual.
The car is drinking around 12.5L/100km (18MPG US, 22 MPG UK). This seems to be much higher than for other 3.0TDI drivers, according to what I read on the forums and on spritmonitor.

I checked the car using VAGCOM and these errors popped up.



> 3 Faults Found:
> 008598 - Oxygen (Lambda) Sensor B1 S1
> P2196 - 002 - Signal too High (Rich)
> Freeze Frame:
> ...


Seeing as there are quite a few DIY'ers on this forum, can anybody tell me where I should start looking to fix this issue?


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## gwiken65 (Jul 8, 2016)

tuut said:


> Hi fellow Phaeton drivers,
> 
> the engine check light has been on for a little while now, with fuel consumption higher than usual.
> The car is drinking around 12.5L/100km (18MPG US, 22 MPG UK). This seems to be much higher than for other 3.0TDI drivers, according to what I read on the forums and on spritmonitor.
> ...


Hi.
I would start with the lambda sensors and check vacuum hoses. Also cabling to the sensors. If the signal is lost from the sensors the ecu uses an uncalibrated value and the car works, but not at it's optimum. Also the regulation loop is decreased with a sensor missing.
Wiken 😊

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## tuut (Sep 13, 2016)

Thanks for the reply.
Might be a dumb question, but where would I find the B1 S1 lambda sensor? Unfortunately the workshop manual seems to be off no help here.


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## gwiken65 (Jul 8, 2016)

tuut said:


> Thanks for the reply.
> Might be a dumb question, but where would I find the B1 S1 lambda sensor? Unfortunately the workshop manual seems to be off no help here.


They are usually mounted on the exhaust pipe before the catalyst. And measures the oxygen left in the exhaust. It works on high temperature, so that's why it's placed there. 
Wiken 😊 

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## tuut (Sep 13, 2016)

I have found where the lambda / O2 / Oxygen sensor is located, being right behind the turbo at the back of the center of the engine when looking at it, with a small cable heading toward a compartment which houses the connection on the firewall.
The connection seemed to be fine.
However I am unsure how to test whether the sensor is still good. 
I looked up how to, but keep coming up with different ways, each mentioning how another shouldn't be used to test the sensor.
_Any ideas before I simply order another one to replace the current one?
_
Unfortunately the workshop manual is truly completely useless with this matter. 
Searching for the removal or replacement of the lambda sensor keeps referring you to one small and useless picture, giving no insight whatsoever.


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## gwiken65 (Jul 8, 2016)

tuut said:


> I have found where the lambda / O2 / Oxygen sensor is located, being right behind the turbo at the back of the center of the engine when looking at it, with a small cable heading toward a compartment which houses the connection on the firewall.
> The connection seemed to be fine.
> However I am unsure how to test whether the sensor is still good.
> I looked up how to, but keep coming up with different ways, each mentioning how another shouldn't be used to test the sensor.
> ...


This is from the top of my head and it's 6 a'clock in the morning. The sensor output is very narrow and should give a voltage output betwen 0 and 1 volt when working. That voltage will change very fast to max and min and is very hard to test. 

One thing is a vacuum leak. That's quite common, a smal hose that is broken. It usually gives an engine fault light (MIL-light on).

If no one else in the forum has any idea or experience with the symptoms of a bad sensor I'm afraid that your only option is to use a new one. 
I have replaced it on other cars with good results.

Wiken 

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## tuut (Sep 13, 2016)

Thanks again, I ordered a new one from Bosch.
Bosch 0 281 004 148 to be precise.
I'll let you know how it turns out!


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## gwiken65 (Jul 8, 2016)

tuut said:


> Thanks again, I ordered a new one from Bosch.
> Bosch 0 281 004 148 to be precise.
> I'll let you know how it turns out!


Good luck. 
Wiken  

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## tuut (Sep 13, 2016)

I replaced the sensor, tightened to 50nm.
Cleared the codes using VCDS.
Fingers crossed that was it!


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## phaetonjohn (Oct 24, 2014)

tuut said:


> The car is drinking around 12.5L/100km (18MPG US, 22 MPG UK). This seems to be much higher than for other 3.0TDI drivers


Man, that's what I get in my V8! My sympathies!!



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## tuut (Sep 13, 2016)

Seems that wasn't it, the check engine light is on again.
Or that was one of the issues, who knows right? 
The old one seemed kinda worn anyway.

I'll check the codes using the VCDS later today.


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## tuut (Sep 13, 2016)

OK, so the check engine light is indeed due to the following



> 1 Fault Found:
> 009261 - Exhaust Gas Temperature Sensor; B1 S3
> P242D - 000 - Short to Plus
> Freeze Frame:
> ...


I read on another forum, possibly from another car, that Bank 1, Sensor 3 is the sensor behind the DPF.
Anybody who can point me in the right direction, yet again?

EDIT:

I checked the workshop manual, there is no sensor 3.
There is however a gas temperature sender 1 and a sender 2, see picture.
Number 7 comes later, temperature sender before particulate filter -G506-. 
I suppose that's the one, I'll be looking for the part number now.


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## gwiken65 (Jul 8, 2016)

tuut said:


> OK, so the check engine light is indeed due to the following
> 
> 
> 
> ...


From the top of my head, sensors DTC can be using the same number because it's a sensor-bank. So that could be why it's missing. That's what I remember from the OBD2 lists I used when developed my own software. 
Wiken 😁 

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## tuut (Sep 13, 2016)

So, which one should I replace according to you? Number 7 on the picture, or another?


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## Gabs08PHTN (Jan 6, 2011)

Hi,
I know it is basic stuff, but did you checķ the condition of the air filter. That could lead to high fuel consumption too regardless of the temperature sender.
In front of the firewall there is a cover that protects most exhaust related senders conections. Perhaps it is also worth inspecting them.

Gabriel


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## tuut (Sep 13, 2016)

Hi,

I recently replaced the Xenon HID's, the air filter had to come off when I replaced them.
The filter seemed fine back then, except for some debris I cleared before reinstalling.

The connections on the firewall seemed fine too, I checked them when I replaced the O2 sensor as mentioned earlier.


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## gwiken65 (Jul 8, 2016)

tuut said:


> So, which one should I replace according to you? Number 7 on the picture, or another?


Hi.
I looked thru my files and I found DTC P0147: O2 sensor circuit malfunction (bank1 sensor 3).
From P0130 to P0167 are O2 sensor codes depending on fail.
P0130 to P0147 is bank 1 sensor 1 thru 3.
So that's what I have. 
I should go for the same bank.
Wiken 😁 

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## tuut (Sep 13, 2016)

Others told me that this issue might be related to a clogged DPF.
So, I was looking to do a forced DPF regeneration, and noticed something.
I followed the guide according to the rosstech page, here.
Everything goes fine, the VCDS shows the 10016 code, which starts the procedure, as accepted, but then nothing happens.
If I open up the measuring blocks, it shows the procedure as aborted.

MVB 100.4: Regeneration Abort recognized (0 = No Abort/1 = Abort recognized)
This one shows 1 right from the start.

But I also noticed that another measuring block, which shows the temperature before the DPF is stuck/faulty, I believe so anyway as it always showed 607.7°C.

MVB 102.2: Temperature before Particle Filter



Could be that the procedure is aborted because of the faulty temperature sensor, looks like I'll be changing it anyway.


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## entwisi (Feb 19, 2013)

Was the car warmed up properly when you tried the regen? IIRC it has to be at > 70C for oil temp before it will run the regen. it also can't have any DTC error codes for Engine or that will also block it.


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## gwiken65 (Jul 8, 2016)

I saw that one could also buy an additive to pour into the fuel. It's suppose to increase the exhaust temperature to burn the DPF clean.
Have any of you tried this?
Maybe it's just bullsh**...🤔
Wiken 😊 

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## tuut (Sep 13, 2016)

Car was hot, faults were cleared, still nothing was happening.
Only reason I could think of is that the temp sensor is faulty, which I think it is, and that sensor somehow functions as a fail safe so your car won't burn up during the regen.

And I did put an additive in the tank, guy at the shop said its widely used by dealers as well, way easier than removing the DPF to clean it anyway. 

I just replaced the 2 front wheel bearings by the way.
Please, never ever attempt to do it by yourself unless you have all the tools and more. :banghead::laugh:


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## n968412L (Apr 23, 2009)

tuut said:


> Please, never ever attempt to do it by yourself unless you have all the tools and more. :banghead::laugh:


Good advice that I will have zero trouble in following to the letter!


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## tuut (Sep 13, 2016)

By tools, I mean the big guns.
I was lucky we could use a friends work shop to work on the car, the tools are meant for busses.


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## tuut (Sep 13, 2016)

Took me a while to find what the exact part number was, but thanks to a call to the VW dealer, and some googling, I ended up with this pic.
Part number is 059906088B if I'm correct.


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## tuut (Sep 13, 2016)

Was going to try a last time to see whether it might be the connectors after all.
I found the culprit once I looked a bit further. :laugh:
Weird to have it snap there, as there does not seem to be anything which could cause tension, or even touch.


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## tuut (Sep 13, 2016)

Replaced the part with a salvage, error persisted.
Replaced the salvage with a new sensor, which cost approx 175€, the error is now gone!


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## gwiken65 (Jul 8, 2016)

tuut said:


> Took me a while to find what the exact part number was, but thanks to a call to the VW dealer, and some googling, I ended up with this pic.
> Part number is 059906088B if I'm correct.


Hi tuut.
From where does this picture come? 
Now I have seems to have the same issue.
I guess you replaced this sensor from under the P, before the DPF?
Wiken 

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## JCJ (Nov 26, 2013)

Gwiken, find it here:

https://nemigaparts.com/cat_spares/etka/volkswagen/phae/710/906150/
This is for 2011 model

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## gwiken65 (Jul 8, 2016)

JCJ said:


> Gwiken, find it here:
> 
> https://nemigaparts.com/cat_spares/etka/volkswagen/phae/710/906150/
> This is for 2011 model
> ...


Thanks John.
Wiken 

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