Needing information about fault code 205C16 (temperature sensor AdBlue tank has a short to ground). I pulled the preheater assembly out and tried to find a short and the resistance reading were between 4.2k ohms and 14K ohms, so I wonder if the short may be in elsewhere. Any suggestions?
Back ground information: 2013 ML350 bluetec with 59,000 miles, recently purchase, replaced soot sensor due to another fault code. It also smells like ammonia and when I pulled the AdBlue tank it was about 1/2 full and I filled it about 2,000 miles ago. I think the last couple of weeks it has been pumping way too much AdBlue.
Can anybody tell me what the resistance readings should be from pin to pin?

 

but shouldnt the temperature sensor be something different than the pre-heater assembly??

 

the MB dealer said I need part # 166-471-07-75 and it is called a preheater. From what I can figure out, this assemble includes the adblue tank heater, level sensors and temperature sensor. After messing with it more today, I found out that between 2 pins the resistance dropped from 10 k to .5 k ohms when I put it in water. I am now believing MD may be right, but $1,300 is more than I want to spend for a temp sensor. I found that XeMODeX will rebuilt it for $499 plus shipping. Has anybody used XeMODeX and how did they perform?

 

I used XeMODex this week. The kits were on BO for a few weeks, XeMODex said that they are launching the BMW product line and demand has drained their stock. They knocked $100 off the R&R cost for me $399 vs $499. Old part was sent out Wed PM and back to me Friday AM. Just installed and cleared the alarm. The did a bench test and it showed a failed heater. Service includes new heater (much more robust than the Bosch) a new temp sender and level sensor.

 

Another option is to install a emulator.. Guy sells them through a youtube channel
I've installed a bunch of them basically it tricks the cdi module that the addblue system
is working normal... basically it bypasses the pump/ heater / and nox sensors.

 

Do you have the details on the emulator?

 

Why not to as dealer to repair it under emissions warranty? AdBlue - system it part of emission and warranty is 8 years/80K miles.

 

Nope, In Saskatchewan we do not have mandatory emissions testing, the catch in the MB Emissions is something to the effect of "where requirement exist" not rules, no support..

 

so what you guys are saying is that if the system/heater fails, instead of paying $2000 or whatever to fix it, we can just put in an emulator to by pass the amble system and the car will run as normal?

oh ya, first post. Golf TDI is being bought back so looking to get a 2014 ML 350 Bluetec but worried about the adblue heater issue and the oil cooler gasket leak issue.

 

^ This.

As for the bypass suggestions, the "it failed and I am too cheap to fix it properly so I'm just going to trick the car into thinking it's fine while I spew out toxic gasses from my tailpie" is not a valid approach and often results in peope of my persuasion to call you an areshole and a bunch of other similar niceties.

 

well that escalated quickly.

 

^ You mean me calling a cheat a cheat? Yeah, I have a tendency to speak my mind, especially when it concerns issues that are clearly wrong. According to the logic of the users suggesting the use of the cheat device, I guess VW didn't do anything wrong either when they decided to cheat with their diesels... right?

 

I've noticed you like to speak your mind from other posts as well. But there are ways to answer someone's question and providing knowledge to them and there are ways of being a dick about it. Why not just answer the question and provide your opinion after that? I initially thought the emulator could bypass the fault and have the car run as normal. Like when I bypass the brake pad wear sensors on my cars. I change my own tires and inspect my brakes periodically so I have no reason to replace a $20 - $40 sensor every time my pads are getting close to be replaced.

Some people here haven't used a car with an adblue system before and are looking to purchase one. I have some questions about a $2000 repair that seems to be quite common. Maybe Mercedes continues to use the same failing parts? Maybe it's something else? I'd like to know some options and what the repair is like before a purchase like this. Regardless if it's under warranty or not.

 

King Luis - you're new and I'll give you the benefit of the doubt here... but you are suggesting that me jumping on the "solution" offered by xcentzneb is me being a dick, yet that he and those like him that buy and use these devices are not? You're knowledgeable enough to bypasss a brake pad wear sensor indicator and you obviously know what it does, you're smart enough to do your research beforehand to find out about potential issues on the car you're thinking of buying, but you actually think that a device that bypasses the whole emission control system might somehow be a legitimate fix - and you own a diesel VW to boot? Do you also believe in Santa Claus?

As for the issue at hand, not one but two solutions were already presented by others. First and foremost, that part of the vehicle is warranted for 8 years, not 4 - which means that on every single W166 ever made that's under 80K miles it would still be replaced under warranty. Second, even if someone has done over 80K miles, the xemodex rebuild that holtl1 suggested is under $500. Last but certainly not least, let's have a little reality check here... an ML is a premium luxury vehicle. Do you really expect that maintenance is going to be cheap once things start to wear out? I have never owned a premium european car that did not require $3K+ annually in repairs and maintenance after the first four years (and I've owned a lot of them)... so if you're hoping to buy someone else's used goods insted of a new Kia or Toyota and hope that it will not cost you the usual 5% of the original selling price of the vehicle to keep it on the road betweeen years 5 and 10, I am afraid you're in for a very nasty surprise. A $2K repair is par for the course... either be prepared to shell out the dough or look at something newer and less expensive.

 

XeMODex update - all good after 2,000 Km and week of -30c weather here in Saskatchewan. For BlueTec owners who will all see this issue - XeMODex is much improved solution to the Bosch OEM part. Costs for the whole project $399 tax, shipping At $22 FedEx overnight and 3ea 9.3l jugs of DEF @$12.95 here in Regina at Home Depot of all places. (Went to the check out and they had a pallet of DEF in the aisle, why not.) All in $530 and 3 - 4hrs total labour, dealer quote was $1,290 +++ my guess was $1,500 out the door.

 

good day

my engine light came on and a strong smell of adblue with smoke coming from exhaust. you can even see the adblue dripping from exhaust tail pipe and crystallizing on exhaust tip. i put in my diagnostics and it come out with 205c16 the temp sensor "adble tank has a short to ground. would the replacement of the heater unit fix this issue. is the excess pumping of the adblue due to this short circuit? or due i have another issue. i dont understand why a short in the temp senor would make the system pump excess adblue. if anyone could help it would be much appreciated.

 

Did u end up getting details?
K.georges@hotmail.com

 

Good day

yes it was the heater unit inside the adblue tank. It got replaced and all back to normal.

 

I have these check engine light problems with the adblue heater and particulate filter sensor. The heater is programed to come on and melt the adblue fluid when the temperature gets below 20F which may happen about five days a year where I live and I may not even drive the car on those days. I had it repaired under warranty the first time and I had to call the mercedes head office to get the warranty enforced at the dealership. The soot sensor may or may not be working as there has been no decrease in mileage or performance. Your assumption that the mercedes adblue system works any better than volkswagen system is questionable. I would prefer that the check engine be available to turn on when a serious engine issue occurs and not pay thousands of dollars to make the light go out when the pollution control system is functioning properly.

 

hello, I have the same problem! What did you replace in the end ?

regards

kelvin