Home > General & Technical (L663) > How does DEF fluid work? |
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blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17367 |
Wikipedia explains the chemistry and consumption better than I can: https://en.wikipedia.org/wiki/Diesel_exhaust_fluid and https://en.wikipedia.org/wiki/Selective_catalytic_reduction
The characteristics you describe such as the smell and the running fan seem to be general characterstics of modern diesels with SCRs, SWMBO's Skoda Yeti having exactly the same characteristics. I had always assumed but without giving the matter much thought that the fan was connected with DPF regeneration, since there is usually a smell of great (but not alarming) heat at the same time, but her L200, which is actually a year younger than the Yeti, doesn't do this and also doesn't have a DEF tank. Thinking now, both vehicles have DPFs but I suspect that only the Yeti has an SCR cat as opposed to a 'normal' cat. I now wonder if it is the Selective Catalytic Reduction process rather than the DPF that is doing this. Hopefully someone who really knows what they're talking about will provide an explanation! |
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19th Aug 2020 9:58am |
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jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8021 |
if its anything like the audi miles to left for the adblue it will show very little change over 8 or 9 mths and then plummet in a matter of days! or could just be my wifes drivnig! Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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19th Aug 2020 11:31am |
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lohr500 Member Since: 14 Sep 2014 Location: Skipton Posts: 1316 |
Interesting comment jst.
My Skoda Superb did the same thing and so does my Wrangler. Both with no obvious changes in driving style to cause an increase in consumption. I just keep a 10l drum of it in the garage so I know I have enough on hand when needed. The Wrangler needs 10 litres around every 3000 miles or so. The last lot I bought was £16 for 2 x 10 litres, so not an expensive carry on. |
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19th Aug 2020 1:02pm |
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milesr3 Member Since: 12 Feb 2013 Location: Suffolk Posts: 873 |
Which says "The injection rate of DEF into the exhaust depends on the specific after-treatment system, but is typically 2–6% of diesel consumption volume. This low dosing rate ensures long fluid refill intervals and minimizes the tank's size (and intrusion into vehicle packaging space)". FWIW my Mercedes seems to be nearer to 1.5% of diesel consumption volume, based on a fag-packet calculation of not needing to refill the 22l AdBlue tank in-between 15,500 mile service intervals. Last edited by milesr3 on 19th Aug 2020 4:34pm. Edited 1 time in total |
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19th Aug 2020 1:33pm |
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Tim in Scotland Member Since: 23 May 2007 Location: The Land that time forgot Posts: 3753 |
I noticed in the most recent “I don’t like the new Defender” video That he said the car had done 5000 miles and he had several DEF fluid level warnings scrolling on the screen. That was what prompted me to check mine!
Click image to enlarge Pangea Green D250 90 HSE with Air Suspension, Off-road Pack, Towing Pack, Black Contrast roof , rear recovery eyes, Front bash plate, Classic flaps all round, extended wheel arch kit and a few bits from PowerfulUK Expel Clear Gloss PPF to come 2020 D240 1st Edition in Pangea Green with Acorn interior. Now gone - old faithful, no mechanical issues whatsoever ever but the leaks and rattles all over the place won’t be missed! |
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19th Aug 2020 1:42pm |
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Roger Member Since: 26 Apr 2018 Location: Hampshire Posts: 71 |
Tim, when you do need to top up the AdBlu then toolstatio/screwfix are actually really competitively priced due to supplying various trades with copious quantities for their work vans, much cheaper than the local forecourt
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19th Aug 2020 2:01pm |
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Tim in Scotland Member Since: 23 May 2007 Location: The Land that time forgot Posts: 3753 |
Cheers for the tip Roger. Pangea Green D250 90 HSE with Air Suspension, Off-road Pack, Towing Pack, Black Contrast roof , rear recovery eyes, Front bash plate, Classic flaps all round, extended wheel arch kit and a few bits from PowerfulUK Expel Clear Gloss PPF to come
2020 D240 1st Edition in Pangea Green with Acorn interior. Now gone - old faithful, no mechanical issues whatsoever ever but the leaks and rattles all over the place won’t be missed! |
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19th Aug 2020 2:25pm |
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J77 Member Since: 04 Nov 2019 Location: Fife Posts: 3393 |
My Velar gets about 6000 miles on a tank, my D4 used to get 11000 miles on a tank, but temperatures and driving styles all have an impact. I filled up with Aldi AdBlue, it was £4.99 for 6 litres, ran sweet as a nut, according to my dealer Halfords AdBlue has caused issues in the past.
You will get plenty warning when it’s running low, if it runs out it won’t start. |
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19th Aug 2020 2:41pm |
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blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17367 |
I wonder if it was full to start with. |
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19th Aug 2020 4:13pm |
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J77 Member Since: 04 Nov 2019 Location: Fife Posts: 3393 |
Every chance, it seems to be over looked by a lot of dealers.
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19th Aug 2020 4:21pm |
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RDR Member Since: 27 Apr 2018 Location: Derbyshire Posts: 592 |
My D4 used to get about 10k miles, the current D5 started complaining it was thirsty after 6K but I have a sneaking suspicion it wasn't full on delivery. 110 MY23.5 X Dynamic HSE
RR MY23 HSE PHEV D5 MY19 HSE - Now Sold D4 MY16 HSE Luxury - Now Sold D4 MY12 HSE - Gone D3 MY06 S - Gone but not forgotten |
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19th Aug 2020 5:19pm |
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lohr500 Member Since: 14 Sep 2014 Location: Skipton Posts: 1316 |
I wonder what the dealer charges for the privilege of procuring 10l of Adblue from them vs Halfords? It's all supposed to be to ISO 22241 standard anyway. Another example of Main Stealer fake news, or fact? |
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19th Aug 2020 6:13pm |
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Pacha Member Since: 23 Feb 2020 Location: North Yorkshire Posts: 772 |
£9.99 for 10 litres @ Toolstation (Redex brand).
Don't want to be paying too much for urea.................. Rgds. Chris |
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19th Aug 2020 6:15pm |
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J77 Member Since: 04 Nov 2019 Location: Fife Posts: 3393 |
£29.99 for the dealer to top up or no charge with the service plan. No idea what they charge just for a top up bottle. I’ve no idea if it’s true, they just said two owners had DEF system issues and both had used Halfords AdBlue. |
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19th Aug 2020 6:44pm |
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