DEF consumption, normal?

[bill-e]

On my way to work this morning my Rebel gave a message to fill the DEF or the vehicle won’t start after 800 km, the truck has 7,079 km and I put 17 litres of DEF so just over 400 km/litre of DEF, does anybody know if the DEF
consumption changes much in the winter? I live 1000 km north of the border and the temperature goes down to -40C or -40F. I am a bit worried about the DEF freezing, the fluid freezes at -11C or 12F, I do park in an insulated garage at home and the truck will be plugged in at work.

EcoD has some heated DEF lines though I don't think that the tank itself is heated. EPA allows for the DEF system to be inoperable because of frozen DEF for some period of time, I've read 70 miles, before the EVIC starts throwing up error messages. As you drive the truck the lines defrost as does the tank.

Don't fill the tank more than 3/4 full as DEF expands when frozen.

I wouldn't stress over this.

 

[Aseras]

The def system will disable at -10c from what I’ve read and will resume using def when it thaws out.

wonder if that means there's a magic trick sensor mod....

 

[bill-e]

wonder if that means there's a magic trick sensor mod....

Someone would have figured that out by now if there was I read that the computer only allows the def system to be turned off for a defined number of miles....but it's too much work for no gain to do the research to find out for sure

 

[Rossum]

I don't think that the tank itself is heated.

I would be really surprised if the tank didn't have a heater. I mean it's down there under the truck in the ambient air. What happens if you wanna drive 700 miles (instead of just 70) in really cold temperatures? The DEF in the tank would never thaw.

FWIW, we just replaced the heater in the DEF tank of our 2015 Touareg. It's not needed this time of the year, but it was throwing codes. It was a bit of a pain since the exhaust had to be dropped to get to it.

 

[bill-e]

I would be really surprised if the tank didn't have a heater.

My understanding is that while the Ecodiesel does have a DEF heater, the heating element is part of the feed line that goes from the tank to the injector site and not in the tank.

 

[Rebelguy2020]

Has anyone noticed the humming sound after you chut your engine off, sounds like a small servo motor, it is on for awhile, someone told me it’s the DEF being pumped back to the tank.

 

[J-Cooz]

Has anyone noticed the humming sound after you chut your engine off, sounds like a small servo motor, it is on for awhile, someone told me it’s the DEF being pumped back to the tank.

Yep I've heard it. Always wondered what it was

 

[Aseras]

The only sound I hear is the air suspension leveling out the rear sometimes.

 

[Rossum]

My truck came from the dealer with the DEF gauge reading full and the salesman stated he personally filled it. I was skeptical about that claim, but he pointed down the street at their own fuel station, with a DEF pump.

First DEF re-fill:
2582 miles on the clock. Fuelly says my average since the getting it has been 25.1, so just over 100 gallons of fuel used. DEF gauge was at 3/8. I just added entire 2.5 gallon jug. Powered on the truck. DEF gauge did its dance and returned to 3/8. Bah! Waited a few seconds, and it went to 7/8. OK! That's accurate enough for me, especially considering my two DEF-using diesel VWs had no indication how full their tanks were at all.

Assuming it was really down to 3/8 and the tank capacity is 5.75 gallons, I've used ~3.6 gallons and the rate has been about 3.5% of fuel use, or about 720 MPG.

 

[Rebelguy2020]

My truck odometer rolled past 012345.6km, my wife laughs at me because I like to see such numbers or repeating numbers.

My truck had 7000km on my first def refill, and it’s now getting near the 1/4, so I keep a 3.78 litre jug in the Rambox. I want to wait until I get the message to add def. I spent last week at my son’s place, he’s 300 km away from my place, my truck was parked outside all the time, no garage there, and the def in the Rambox froze solid, I should have brought it in the house.
I’m back home now and around 12500 km on the truck, and still no message for def.
Has anyone noticed that on startup the def gauge shows lower and it goes up after driving a bit, mine now goes from 1/4 to almost 3/8.
I don’t think my truck will make it to 14000km before getting the def message, I barely towed this winter but idling time for warm up must consume more def.

 

[Sascwatch]

My truck odometer rolled past 012345.6km, my wife laughs at me because I like to see such numbers or repeating numbers.

My truck had 7000km on my first def refill, and it’s now getting near the 1/4, so I keep a 3.78 litre jug in the Rambox. I want to wait until I get the message to add def. I spent last week at my son’s place, he’s 300 km away from my place, my truck was parked outside all the time, no garage there, and the def in the Rambox froze solid, I should have brought it in the house.
I’m back home now and around 12500 km on the truck, and still no message for def.
Has anyone noticed that on startup the def gauge shows lower and it goes up after driving a bit, mine now goes from 1/4 to almost 3/8.
I don’t think my truck will make it to 14000km before getting the def message, I barely towed this winter but idling time for warm up must consume more def.

My def gauge is all over the place once I get below a half a tank. I too am waiting for the “refill def” message before I add any.

 

[bill-e]

I have 4900 miles of which 1k was towing and my gauge is just under 1/2. It was filled by the dealer when I bought it.

 

[tom318]

At ~5500 miles I filled mine. Had 200 miles left on DEF range and it started threatening me it wouldn't start if it fell below some set range. That was with ~900 miles of towing and then basic commuting. I average about 26mpg per tank on commutes and minimal idle. 1-2minutes before I take off.

 

[WXman]

Has anyone noticed the humming sound after you chut your engine off, sounds like a small servo motor, it is on for awhile, someone told me it’s the DEF being pumped back to the tank.

The under hood humming is apparently the pump running coolant through the turbo to protect it from hot shut-down.

There's also an electric butterfly valve in the tailpipe that I can hear sometimes when I shut the truck off. Apparently that valve creates the backpressure to operate the low side EGR.

As far as DEF usage mine has averaged roughly 1 gallon per 1000 miles.

 

[Rebelguy2020]

The under hood humming is apparently the pump running coolant through the turbo to protect it from hot shut-down.

There's also an electric butterfly valve in the tailpipe that I can hear sometimes when I shut the truck off. Apparently that valve creates the backpressure to operate the low side EGR.

As far as DEF usage mine has averaged roughly 1 gallon per 1000 miles.

Thanks for the reply, the turbo cooling makes sense, the butterfly valve in the tailpipe I have never heard of and I don’t understand it’s function, maybe someone could elaborate on that.
Your def is right on par with mine, well at least equal to my first fill up.

 

[J-Cooz]

I believe it does drain the def out of the lines so they don't freeze for us in the north. I can hear it running after every shut down.

 

[Malodave]

I had 1/2 tank of DEF from the Dealer. Went 1500 miles
and was down to 44 miles left of DEF. Went to the nearest
Truck Stop, The DEF pump was down. They pointed me to the
jugs on the shelf. One Gallon was $9.95, 2.5 Gallons was $22.99.
I could not get back in my truck quick enough.

Ended up at the local Home Depot. Got two 2.5 Gallon Jugs for $25 total.
On the way home I spotted a Local Sunoco sign with DEF at the Pump for
$2.29 Gal. This Station was less than half of the way to the truck stop.

I am just over 3K miles and about 5/8 full on DEF. So I have used about
4.7 Gallons of DEF so far.

Malodave

 

[WXman]

Thanks for the reply, the turbo cooling makes sense, the butterfly valve in the tailpipe I have never heard of and I don’t understand it’s function, maybe someone could elaborate on that.
Your def is right on par with mine, well at least equal to my first fill up.

If you crawl under your truck and look at your tail pipe near the rear axle, you'll see a solenoid activated butterfly valve. This is my understanding of its purpose though I could be wrong: These trucks use a high and low pressure EGR. The low pressure side can be seen immediately downstream of the DPF. It pumps cleaner exhaust back into the engine under certain circumstances. In order for this portion of the exhaust to flow properly, it needs more backpressure in the exhaust system. To accomplish this, they're using the butterfly valve in the tail pipe to effectively "cork up" the exhaust on purpose under certain circumstances.

As I try to imagine this function happening while driving, it's no surprise that lag and non-linear driveability issues have been common complaints with this engine. Trying to balance a drive by wire throttle, natural lag of a turbo charger, and purposeful alteration of the exhaust flow all in concert with each other seems like a tuning nightmare!

 

[Sascwatch]

If you crawl under your truck and look at your tail pipe near the rear axle, you'll see a solenoid activated butterfly valve. This is my understanding of its purpose though I could be wrong: These trucks use a high and low pressure EGR. The low pressure side can be seen immediately downstream of the DPF. It pumps cleaner exhaust back into the engine under certain circumstances. In order for this portion of the exhaust to flow properly, it needs more backpressure in the exhaust system. To accomplish this, they're using the butterfly valve in the tail pipe to effectively "cork up" the exhaust on purpose under certain circumstances.

As I try to imagine this function happening while driving, it's no surprise that lag and non-linear driveability issues have been common complaints with this engine. Trying to balance a drive by wire throttle, natural lag of a turbo charger, and purposeful alteration of the exhaust flow all in concert with each other seems like a tuning nightmare!

The pollution control devices on these trucks must make programming a nightmare for any manufacturer putting out a diesel vehicle. After the issues FCA had with the last gen eco diesel I bet they focused on emissions over drivability to keep themselves out of trouble.

It is amazing what they can get out of such lower displacement engines nowadays, I would love to see someone like gale banks put some time into the eco diesel or any of the 3 litre diesels to see what they are really capable of.

 

[Rebelguy2020]

If you crawl under your truck and look at your tail pipe near the rear axle, you'll see a solenoid activated butterfly valve. This is my understanding of its purpose though I could be wrong: These trucks use a high and low pressure EGR. The low pressure side can be seen immediately downstream of the DPF. It pumps cleaner exhaust back into the engine under certain circumstances. In order for this portion of the exhaust to flow properly, it needs more backpressure in the exhaust system. To accomplish this, they're using the butterfly valve in the tail pipe to effectively "cork up" the exhaust on purpose under certain circumstances.

As I try to imagine this function happening while driving, it's no surprise that lag and non-linear driveability issues have been common complaints with this engine. Trying to balance a drive by wire throttle, natural lag of a turbo charger, and purposeful alteration of the exhaust flow all in concert with each other seems like a tuning nightmare!

That is probably why when the truck idles there is barely any sound or exhaust pressure coming from each of the tail pipes.
I plan on keeping this truck a long time, my previous was a 2011 Outdoorsman, I sure hope all those emission controls last.
I’m pretty sure that the emission system has its own type of warranty, i think it is 6 years, that was the reason for most exhaust system going to stainless, the manufacturer was responsible for the repairs with premature failures.