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Diesel Ad Blue tank heater fault

95K views 38 replies 21 participants last post by  NROdieselguy  
#1 ·
Hello all, new member. Need some input.
Feb. 2012 I bought a 2010 GL350 CPO with 22,650 miles on the clock. Added the MB extended warranty for 2 years or 135,000 miles and 2 prepaid services. 30,000m service done with out any trouble but 40,000 I had to fight it out with dealer/MB USA to get the trans service completed. The dealer also blew right pass the required service task of ADBlue evacuate and refill said "top off was all that was needed". 50,000m service was completed at a local shop that does mainly MB work all tasks completed as per MB booklet.
Now to the kick in the teeth. Engine check light pops July 2013 @52,950m. Take the GL to the shop, codes are 20BD1B & 20BE1B. Fix $1562.44 for an Internal Fault with the AD Blue tank heating element. Part is in stock (must be a fast moving item) #A1644710975 ($1100.00) for a 2 quart plastic tank and some wiring & sensors. However the dealer states MB USA CPO WARRANTY will not cover this part and repair. Has anyone else been down this path? Please relate the out come. Thanks.
 
#3 ·
I was told by my dealer in Canada that they had to evacuate the tank once a year and replace due to crystal build up. Liquid evaporating.

First my car had this done was when I had it for 9 months and 16000kms.

Maybe that might have something to do with the heater problem.

From my experience is definately better to keep the tank always full to avoid this problem.
 
#5 ·
Hi I have some problem on my GL350 2011.
I have extended warranty in Canada and it is covered by the warranty. It is part of emission element.
But before my dealer will replace it. They did some update directive from Mercedes Canada.
So far all is good and engine light is not on but if it comes back. They will have to replace the not just the heater but the whole adblue tank.
 
#6 ·
Here in the USA the ADblue tank complete with heater, sensor and misc. is covered under Emission Warranty. Tank complete lists at a price of $1820.00. However if the tech. goes the repair parts kit route @ $1100.00 NO emission warranty coverage! Neat how all the items likely to fail heater & sensor slip thru the state and FED. emission REGs. The rest of the story is anything ADblue contacts is not covered by the MBusa CPO warranty or Extended Limited Warranty. A 1600.00 Dollar repair at 52,900miles after servicing per factory maintenance booklet at MB shops cuts deep into "the DIESEL economy".
 
#7 ·
AdBlue Tank Replacement

I just did 60k mile service on my 2010 ML-350 BlueTec a few weeks ago and got Check Engine light the other day. Now the dealer said Ad blue sensor bad and the whole tank needs replacing. It is going to cost over $2000. I just research and found this discussion.

Since I don't have any extended warranty, this going to have to come out of my pocket. I am wondering if there is cheaper solution. Can it be repaired instead of replacing? Dealer does not give me repair option. Can this repair be handled by outside shops? I am in Houston, TX. If anyone know good shop who can do cheaper than dealer, please suggest.

Is this adblue system going to fail every 50-60k milage? I am thinking of trading up to GL series with adblue/diesel but if this is making me rethink about Diesel.
 
#8 ·
Adblu/blutec/Diesel Particulate Fluid etc are all the same. They are just one more thing to go wrong - and sometimes they do just that. Check with TrueDelta to find out if Mercedes has better or worse problems with DPF systems than other diesel manufacturers.
 
#9 ·
At 200,000 kilometres, I replaced the heater in my ADBLUE tank (about $1,000).

At 300,000 kilometers, I replaced the ADBLUE line heater (about $800).

I'd get a second opinion .... why replace the entire tank if it's just the heater element ?
 
#14 ·
if you are the original owner and have had your services done at dealer, call MB and ask for assistance. it never hurts to ask.

this is a very common issue with any car maker that uses adblue. all the tank heaters are similar.
 
#17 · (Edited)
I just went through the "failed Adblue tank heater" nightmare for the second time. Options were:

-- pay dealer $2000 to completely replace the tank with heater and pump
-- buy the tank, heater, and pump as one unit for about $1400 and install myself
-- buy an aftermarket heater from Xemodex for about $300 and install myself

I chose the third option even though it was trickier, because the Mercedes heater unit will just burn out again in about 1500-2000 hours (60-70k miles of driving). The first complete tank replacement was covered under the 8/80 Federal emissions warranty (after I pressed the dealership a little) but this time it's on me.

The problem is that the MB heater is too small, and it burns out because it's running all the time trying to keep the fluid warm. It doesn't only run when the tank is about to freeze, it runs when the tank is above freezing too.

The Xemodex heater is considerably beefier, although their one year warranty is not worth much. The install requires above-average DIY skills, including soldering. The instructions provided are not 100% complete so you need to have some experience to fill in the gaps. Cleanliness is key, because tiny dust contamination in the AdBlue tank can cause a problem later.

Basic steps for a 2009 GL (ML and others will be similar):

Before starting completely drain the AdBlue tank. Otherwise it's too heavy. A fluid extractor is needed here since there's no drain plug. Be sure the hose of the extractor is completely clean.

1. Unbolt the tank dust cover (four 10mm plastic nuts) and tank supports (four 13mm metal nuts) and lower it as one unit.

2. Disconnect wire harnesses and hose. Cover the hose immediately with plastic wrap to keep the fluid from crystallizing.

3. Clean the top of the tank of dust & dirt.

4. Disconnect wiring to pump and heater. Photograph where everything goes.

5. Xemodex instructions pick up here. You'll remove the pump (3 Allen bolts), retaining nut, rubber seal and reservoir. Keep cleaning as you go.

6. Xemodex instructions then explain where to cut the heater wires, run the new wires, solder, heat shrink, and re-assembly.

7. Put everything back carefully. Be especially careful to get the rubber seal in correctly. The system needs to be airtight (except for the vents).

8. FILL THE ADBLUE TANK 100% full! People skip this step and it results in a burned-out pump. Filling the tank 100% allows fluid to spill into the central reservoir and fill it up too, so the pump can prime.

9. Plug in your OBD reader if you have one, observe the permanent code P20BE or similar. Go for a Universal Drive Trip (follow instructions exactly) and upon shutting off the engine the code should clear itself. Or, just watch the Check Engine Light go off.


This is a 2-3 hour job, and not hard for someone with the tools and skills, but definitely not for an inexperienced DIYer. Total cost about $340 including 10 gallons of AdBlue.

I don't have long term experience with the Xemodex heater yet but from the looks of it, it's a much better part than what Bosch made.

Keep in mind that the dealer replaces the whole tank because it's easier and you get a fresh pump and temp sensor in the bargain. If money is no object, that's the way to go.
 
#18 ·
I am just blown away by the problems these diesels have.

They cost more to buy. Most of them have a lot of money spent to fix oil leaks. Failure of the Ad Blue system tank/heater has cost many owners serious money. Just wait until the price to replace or clean the DPF gets added to the cost of ownership.

So people think I am going to get a diesel and save a ton of money on fuel by getting better MPGs. This entire generation of the V6 aluminum diesels has been a costly lesson for many owners. The cost of upkeep and paying tons of money to fix issues that were design flaws(oil cooler leak to just name one) has people that are driving these diesels paying more cents per mile than the gasoline models.

For all the diesel owners I really hope the Xemodex replacement helps mitigate some of the cost of the diesel ownership.
 
#19 ·
I should have shared this long ago. Here's my plan I DO NOT add more than 1 1/2 gallons of adblue to the tank. I only add after the dash lamp has been light for 300 to 500 miles. As a life long farmer I understand liquid fertilizer is mixture of water and salts or urea. Over time the urea "salts out" or forms crystals that collect at the bottom of the storage vessel. On the farm we always try to empty storage tanks before adding a new load of urea. Reason being these salt crystals clog nozzles, screens and destroy pumps. Also over time these crystals will cement themselves together to form a dry concrete like rock in the bottom of a storage tank.

If I lost you here's the tie in AdBlue = urea!!!!

MB felt the owner should not be troubled with adding AdBlue. Hence dump the spare tire and install a tank with a 12,000 mile capacity. So the supply spans from one oil change to the next. Then add a heater which speeds separation and after time the element becomes surrounded by salt solids and burns out due to over heating. If the vehicle is not used for towing at 10,000 miles the tank may still be 1/2 full. At this point topping off the tank will only increase problems of salting out.

In my opinion MB builds their product to be trouble free thru out a 2 year lease! Stepping outside the 2 year lease/ 50,000 mile warranty box sometimes requires a different game plan. One example dumping the rough riding run flats by replacing the tire and wheel assy with a tire that has a side wall. Resulting in not beating the air ride the a early death.
 
#21 ·
I'm not why do you want to keep a tank half empty, if the heater element located in another container within tank space. To me less ad blue in the heater container is making crystallization process, since if it's not full it will react with air, that is why its crystallized.
btw it's not all tank heats up just the small container.
 
#23 ·
I base my ADD adBlue only as needed plan on the following. The MB 2010 model year maintenance booklet lists this item as "Required service Work" every 40,000 miles. "AdBlue evacuate and fill up (engine 642)". After completing a 40,000 mile service at an area MB dealership for my 2010 GL 350 I found the following. The amount of AdBlue invoiced was not enough to fill the tank after an "evacuation". Upon questioning the service rep. I was told the task of evacuating the tank was unnecessary and no longer a required service item! Later when the heater burned out I was refused any warranty coverage due to an incomplete 40,000 mile service. So I paid the repair invoice out of pocket. If MB wants the tank emptied every 40,000 then I believe it should be done.
A few lessons learned.
1 In hope to extend the service life of the tank heater. I allow the vehicle to empty the tank thru normal driving. Kinda like the first in first out inventory system.
2 When buying our new 2015 GLK 250 I did not grace the above mentioned dealership with my business. You will get burnt getting to close to the "SUN"!
3 I can not trust dealerships to complete this service item! So-
4 When the GLK is due an evacuation. I will shop yard sales for a low cost shop vac and try to suck the Adblue out thru the very small fill hole.
5 Then pay a dealership to complete or fake this task. And hope for the best.

A question for MB to ponder, If the tank needs emptied then why not install a DRAIN?
 
#24 ·
KB2, sorry to say it sounds like you got a lame excuse for lack of warranty coverage. The tank heater does not burn out because of lack of fluid changes. The two things are completely unrelated. The heater fails because of bad design.

Using a Shop Vac to suck out the liquid is probably not a good idea. You don't want to risk introducing any contaminant to the tank. The dealer uses a dedicated evacuation pump, or more likely skips the "evacuate and refill" step entirely as you discovered.

The Adblue formula doesn't "salt out" in the tank during normal use, unless allowed to evaporate. It's very different from liquid urea fertilizer, which is a mix of urea and ammonium nitrate and will salt out at a particular temperature (dependent on the % mix). There's no risk associated with keeping the tank full.
 
#25 ·
What Iridium says is absolutely spot-on! I own several of these vehicles. Evacuating and refilling the DEF is nonsense and there is no benefit to do it. The problems that I have experienced with the tank heater unit are not the heater itself, but rather the temp sensor. There is a temp sensor and also a level sensor, both of which are integral to the heater unit. The sensors cannot be replaced individually, a complete new heater unit has to be purchased. The problem has been known to come from urea crystallizing in the wiring harness and then tripping a failed sensor code. The urea is highly corrosive on copper and a host of other metals. I'm told that there has been a design change (to the heater unit) that addresses this issue. Other than this, the only other issues I've had to deal with in the after treatment system were faulty NOx sensors. And I've had complete tank heater units replaced under factory warranty with absolutely no cost to me and no argument what so ever.
 
#27 ·
I'm in Colorado and experiencing this failure.

I contacted Xemodex and notice their warranty is only 12 months. Has anyone else used this repair except for the one previous poster?

Also, what is the downside if not repaired quickly or at all?

The DEF tank is full, check engine light is on. I don't have an emission test for another 20 months.

What does the repair kit include?

2012 ML 350
 
#28 ·
I have the same code now at 60,000 miles. I'm not going to be happy if I have to pull 2g's out of my pocket.. Has anyone gone the no emission route? Pull all that junk off and put a computer chip in? I hear you get more power and better fuel mileage..
 
#29 ·
There are chips floating around on eBay from European sellers that install in the ODB2 plug and require you to remover certain fuses so it can properly emulate the system. You should be able to get one for under 200.00. Amazon seems to have removed all of the ones that used to be on there.


Sent from my iPhone using Tapatalk
 
#30 ·
Thanks for the DIY. I got the code on my '12 gl350 at 60k miles.. Been driving with the light on for 6 months and it drives me crazy. I am gonna attempt the heater replacement as you did. 3 different Stealers would not cover under emissions warranty which is bullshit.
Also thinking of going to after market chip to eliminate ad blue altogether. Hear anything about them?

I'm looking for a 2010-13 E350 or S350 diesel 4matic. Can't find one for sale in the US. I'm afraid to try the newer 4 cal diesels.