Increased fuel and AdBlue consumption

aditud

Veteran Member
Joined
May 16, 2017
Location
Pittsburgh
TDI
2015 GSW SE 6MT
I picked up a "new" GSW SE 6MT right after the stop sale ban was lifted in the Spring of 2017. Naturally, it had the Phase 1 completed. I sensed no real change in terms of fuel economy from the GSW SE DSG I sold back to VW that same Spring.

Now, fast forward to December 2018 when I had Phase 2 done. Once again, I didn't really notice anything changed. It appears they didn't fill the AdBlue tank while doing Phase 2, nor did they do it when I had the car in for the 30K maintenance service. I had filled it when the car had about 28k miles on it (between Phase 2 and the 30K service), or something like that.

The AdBlue light came on at about 35k, definitely at less than 7k after I had filled it all to the brim myself. Also, starting sometime in August I began noticing increased fuel consumption, achieving around 3mpg less than I used to (I had the car sit for about a month in July while I was on a trip to Europe). On my commute I would routinely achieve 50mpg on my way back driving around 73mph on mostly highway. After August, 48mpg was a rather rare achievement. During October it got worse, maybe 45-46mpg, even though the weather was still fair and warm. This past week we had a couple of mornings slightly below freezing and was barely able to get 44mpg, and this past Friday (when it stayed at around 32-34F throughout the day) I didn't even get the advertised 43mpg.

Anyway, I can't help but wonder whether there's something going on. I certainly didn't expect to have to refill the AdBlue tank after 7k, and I can't really explain this dip in fuel economy, as my driving habits haven't changed.
 

ProfBrown

Veteran Member
Joined
Jan 16, 2019
Location
So Cal
TDI
2015 GSW SE DSG
I have a buddy who quite literally over a camp fire was talking to me about the same issue on his 15 Jetta TDI 6mt. Subbed to see what people say.


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Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
More than likely winter treated fuel. See if it goes back up in the spring. Even though the temps may be warm they are still treating the fuel getting ready for the cold.
 

Nutty 5.0

Veteran Member
Joined
Aug 22, 2014
Location
SE PA
TDI
15 GSW SEL TDI 6MT
I'll chime in for the fuel usage and agree it is likely the winter blends. Mine dropped off in the past few weeks. I'm on the other side of Pa.
 

ProfBrown

Veteran Member
Joined
Jan 16, 2019
Location
So Cal
TDI
2015 GSW SE DSG
I'll chime in for the fuel usage and agree it is likely the winter blends. Mine dropped off in the past few weeks. I'm on the other side of Pa.


For reference the buddy of mine was having his drop drastically in Ventura, California. So yes we get a winter blend but I am also on So Cal, and I have not noticed this mileage drop or increased def usage.


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Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
I have read here that a full dpf can also cause this to happen. A monitoring app like VagDPF would show the soot and ash load.
 

sloinker

Veteran Member
Joined
Jun 27, 2015
Location
Casper, Wyoming
TDI
'15 Sportwagen '15 Golf Hatch
Winter fuel and cold temperatures kill fuel mileage in these TDI's. I easily get above 45 MPG in the summer commute. That MPG struggles to get to 40 in the winter.
 

ProfBrown

Veteran Member
Joined
Jan 16, 2019
Location
So Cal
TDI
2015 GSW SE DSG
Increased AdBlue usage is to be expected with the emissions fix. I too just went through 2.5gal in ~6000 miles.


I have only ever owned my car with phase 2 done and I do about 7500-10k on 2.5 gallons of def. US gallons that is.


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740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
the tank is bigger than 2.5 gallons thou?

My question is is the commute the same? are you driving 20 miles plus per drive?
 

ProfBrown

Veteran Member
Joined
Jan 16, 2019
Location
So Cal
TDI
2015 GSW SE DSG
the tank is bigger than 2.5 gallons thou?

My question is is the commute the same? are you driving 20 miles plus per drive?


Yes I do commute more than 20 mile drives. Minimum drive from my house to town is 25 miles. To school it’s 60. Shy of in town driving to get lunch from work or gym of course. Both those numbers are 1 way off course. And yes the tank is larger than 2.5 gallons, about 5 gallons I hear, but the cans I buy at Walmart are 2.5 gallons and those seem to get me almost get me through if not a tad over the 10k oil change interval.


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740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
7-10K on 2.5gal of def is in line with what you should expect. if you were draining 5 gal or a tank in the same distance i'd be worried.
 

Beeah

Veteran Member
Joined
Dec 19, 2006
Location
Plymouth, MI
TDI
15 GSWs 6MT | 02 Jetta TDI(Sold)
As other have said, winter fuel is a very noticeable difference, colder temps also affect as the air is more dense = more drag. Colder temps also drop tire pressures a LOT so double check those to make sure they are near max.
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
just had to add the first 2.5 gal jug to our passat since i topped up the tank sometime back around 30Kish, currently sitting at 48K.
 

aditud

Veteran Member
Joined
May 16, 2017
Location
Pittsburgh
TDI
2015 GSW SE 6MT
I had the 40k maintenance done a few weeks ago. The guy poured in almost all of the AdBlue from the big OEM jug. That was happening less than 6k miles and less than 5 months after I topped it off back in October.

The FE continues to be pretty bad, and it's still worse on my way back from work (even though that used be the best, it's downhill on the average), worse than any previous winter, even though this one's mild. A few days ago I barely managed 40mpg on the highway, as it was wet and windy. But I used to still get 45mpg in those conditions. The regens happen often.

As I wrote in the original post, I don't know if phase 2 mod is to blame, because for a long while after they did it I didn't notice anything different. Maybe it is the winter blend, I don't know, but I doubt it. And what's up with all the AdBlue consumption? Seems extreme.
 
Last edited:

ticaf

Veteran Member
Joined
Nov 15, 2018
Location
US Mid-Atlantic
TDI
Stock 2015 Golf SW S Manual TDI
I had the 40k maintenance done a few weeks ago. The guy poured in almost all of the AdBlue from the big OEM jug. That was happening less than 6k miles and less than 5 months after I topped it off back in October.

The FE continues to be pretty bad, and it's still worse on my way back from work (even though that used be the best, it's downhill on the average), worse than any previous winter, even though this one's mild. A few days ago I barely managed 40mpg on the highway, as it was wet and windy. But I used to still get 45mpg in those conditions. The regens happen often.

As I wrote in the original post, I don't know if phase 2 mod is to blame, because for a long while after they did it I didn't notice anything different. Maybe it is the winter blend, I don't know, but I doubt it. And what's up with all the AdBlue consumption? Seems extreme.

How many miles on your car? And what is your dpf ash loading
?
 

ProfBrown

Veteran Member
Joined
Jan 16, 2019
Location
So Cal
TDI
2015 GSW SE DSG
I would bet it’s the winter fuel honestly.

As a side note my ad blue usage didn’t change, but my mpg for sure dropped on winter blend here in Cali. That being said last tank or 2 it seems to be getting better. I am beginning to think the winter blend is being phased out here.


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Cuzoe

Veteran Member
Joined
May 24, 2017
Location
Los Angeles
TDI
MK7 Golf S
I can't get a good read on ad-blue usage for my car. I had the car telling me it wasn't going to start a couple thousand miles before my first (dealer) oil change at 10k. But I didn't have to add any before the next dealer oil change at 20K. And I'm due for the 30k service at the dealer and still haven't added any. Bought the car new old stock with less than 100 miles on it 2017.

The only way this makes sense is if the tank was never filled up in the beginning. My paperwork says all fluids were topped off in pre-delivery, although I don't suspect the dealer would have hooked up a diag tool to check ad-blue level. Car was phase I when I bought it, still phase I. I've been running Kerma Stg 1/1+ since 2500-ish miles. Even if the tune reduces adblue usage (and I don't know that it does), I can't imagine I went through most of the initial tank in the short time I was not tuned.

I'm in SoCal also and although I didn't drive the car very much this winter the mpg was noticeably worse. Last two tanks have been closer to what I'm used to seeing. My numbers will be worse than what any of you guys are seeing because my of my 2 mile commute. If I drive straight to work coolant doesn't even get up to temp. Because of that the TDI gets driven to work once, maybe twice a week but it does get driven whenever me and my wife go somewhere, trying to keep miles off of her car.


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Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
You need a special tool to see this. I use an app called VAG DPF and Bluetooth OBDII dongle. Some use the Torque app and I think VCDS can also see this value.
 

aditud

Veteran Member
Joined
May 16, 2017
Location
Pittsburgh
TDI
2015 GSW SE 6MT
You need a special tool to see this. I use an app called VAG DPF and Bluetooth OBDII dongle. Some use the Torque app and I think VCDS can also see this value.
I have the OBDII premium. But I thought it only worked with the OBD app.
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
I have no idea what the OBDII premium is. A bluetooth dongle should work with whatever app and communications tool you have with BT. But the app or software needs to speak VW in order to work. Almost all vehicles communicate in two protocols. OBDII (which is government mandated, limited to emissions mostly) and a proprietary protocol of the manufacturer. You will need something that speaks VW like the apps and software I mentioned. That will usually let you see everything available on the vehicle.
 

aditud

Veteran Member
Joined
May 16, 2017
Location
Pittsburgh
TDI
2015 GSW SE 6MT
I have no idea what the OBDII premium is. A bluetooth dongle should work with whatever app and communications tool you have with BT. But the app or software needs to speak VW in order to work. Almost all vehicles communicate in two protocols. OBDII (which is government mandated, limited to emissions mostly) and a proprietary protocol of the manufacturer. You will need something that speaks VW like the apps and software I mentioned. That will usually let you see everything available on the vehicle.
I meant "professional": https://obdeleven.com/en/products-page.
I don't need credits or whatever to access everything the tool can do.
 

ProfBrown

Veteran Member
Joined
Jan 16, 2019
Location
So Cal
TDI
2015 GSW SE DSG
I can't get a good read on ad-blue usage for my car. I had the car telling me it wasn't going to start a couple thousand miles before my first (dealer) oil change at 10k. But I didn't have to add any before the next dealer oil change at 20K.
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Dealer might be topping you off when you bring the car in. I have heard of some places doing this without owners knowing. Not really a bad thing just a thing lol.

I think I have added 3 jugs of 2.5 gallons of adblue into my car since I got it. I’ve put over 30k on the car to this point in the just over 1 year and 1 month that I’ve owned it. Pretty sure when I got it it wasn’t full cause it only lasted about 10k miles before it needed more. From what I have seen that usually takes about 10k miles to do 2.5 gallons of adblue. But the last time I added some I didn’t get the notification so I dont know. Does seem somewhat irregular. I assume also has something to do with quality of diesel you put in the car and how often you drive the vehicle not at temp and city vs highway driving. With where I live in Cali it can take up to 20 miles before my car gets warm due to hills and ambient temp/not much load on the car cruising on flat roads at under 25 or 60 mph below 1800 rpm.
 

ticaf

Veteran Member
Joined
Nov 15, 2018
Location
US Mid-Atlantic
TDI
Stock 2015 Golf SW S Manual TDI
I meant "professional": https://obdeleven.com/en/products-page.
I don't need credits or whatever to access everything the tool can do.

Yes, with OBDEleven, go to "engine", and then live data, and search for "ash" keyword.

That being said, with only 40k your DPF should be very lightly loaded with ash, UNLESS somebody kept using the wrong kind of oil, which happened to me many times at various VW dealerships ( I had them redo the oil change, happened at 4 different dealerships!!!). I do my own oil change now.
 

leicaman

Top Post Dawg
Joined
Dec 24, 2004
Location
Sheboygan, Wisconsin
TDI
2015 Golf TDI SE, 2005 TDI GLS, RIP
In the winter with winter fuel, I normally get around 42-44 mpg on the freeway jaunts (cruise set at 75) I do. If I stick to the country roads, well then I can get a few more miles per gallon. My mileage is better in the summer as I am no longer running winter tires.
 

AGOODHI

Veteran Member
Joined
Jul 30, 2011
Location
NorCal
TDI
MKVII GSW, MKVI Golf
regarding def consumption, any crystallization in the engine compartment?
 

aditud

Veteran Member
Joined
May 16, 2017
Location
Pittsburgh
TDI
2015 GSW SE 6MT
I did achieve 50mpg trips on my last three commutes (it hasn't happened in months, not even close), with the same fuel in the tank that gave me abysmal mpg last week. So I don't think it's the winter blend, I just think it's related to the increased consumption of adblue. The regens are probably happening too frequently (why, I drive 85% highway only), it just happens I didn't have any for the last 150 miles or so. Anyway, I'm planning to use the OBD tool to check the ash load.
 

ProfBrown

Veteran Member
Joined
Jan 16, 2019
Location
So Cal
TDI
2015 GSW SE DSG
Ironically I visited a different gas station on this most recent full up and mpg dropped a noticeable amount. Driving style stayed the same, commuter mode. At this point I just don’t care as long as I am getting about 250 miles to the half tank mark on my specific car.


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