2013 ML350 BT - P20B9 check engine light and def fluid pump nozzle broke
Junior Member
Joined: Nov 2019
Posts: 18
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From: Toronto
2013 (W166) ML350 Bluetec
You are right and even I am fully aware of. I am ready with all my research for where to buy parts and DIY for replacing the DEF tank heater. In my case, I purchased from a used car dealer in Milton - One price Auto (belongs to JP Motor Burlington). I will not trust the dealer to fix it by replacing brand new heater. In your opinion, what do you think the dealer Technician will do to temporarily delete the fault code which may come back in next 500 kms or may be the next time temp drops below Ad Blue's freezing point?
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W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
You are right and even I am fully aware of. I am ready with all my research for where to buy parts and DIY for replacing the DEF tank heater. In my case, I purchased from a used car dealer in Milton - One price Auto (belongs to JP Motor Burlington). I will not trust the dealer to fix it by replacing brand new heater. In your opinion, what do you think the dealer Technician will do to temporarily delete the fault code which may come back in next 500 kms or may be the next time temp drops below Ad Blue's freezing point?
Whether the tech clears the code is irrelevant. The code will keep coming back until you repalce the heater.
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Joined: Nov 2019
Posts: 18
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From: Toronto
2013 (W166) ML350 Bluetec
No, I never said I bought used parts. I bought used Truck from the used car dealership (not CPO). After owing it on 2nd day cold morning the MIL lit up with P20BE and then I returned the truck to the dealer. I am glad to know that if the code is going to come back, then the dealer will have no other option - either to fix or keep the truck I will reverse the transaction = traded 2016 Ford Edge Titanium Pearl White FWD 2.0 Ecoboost 97,000 kms.
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W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
Ah - understood. Yes, the DEF tank heaters crap out from freezing / thawing cycles. If there is a warranty on the ML purchase and they pay for the repair, you're golden... that is pretty much the only thing that is known to regularly fail and is over $2K from MB (the NOX sensors also go but not quite as often on average). A new one should last you for a number of years.
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From: Canada
ML350 Bluetec 2014
Saw in several threads that this P20E8 issue being discussed, but seems no clear answer to this. May have to bring to the dealership? any thoughts? Thanks.
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W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
It could be a number of things, although if you just replaced the heater unit yourself, my bet would be on an air leak in your newly assembled DEF tank or corroded electrical contacts. Paying the dealership to diagnose and/or fix it at this point is IMHO reasonable.
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From: Canada
ML350 Bluetec 2014
Thanks, Diabolis, because the P20E8 code wasn't there before, my best guess is that the crystalized urea plugged somewhere inside the pump during installation (someone in other thread discussed this possibility), although the pump nozzle was sealed during the process to prevent this from happening, it was still noticed that there are quite some crystal formed around the nozzle. If this is true, it may be possible to get rid of the P20E8 code through replacing the pump. Kind of don't know what to do know. Thank you for your comment.
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W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
RiverX - the nozzle needs to be capped to protect the DEF fluid, which crystallizes very easily when exposed to air. However, ammonia crystals rapidly dissolve in water, so you could try soaking it in water for a few minutes and then rinsing it out with some distilled water - assuming that the pump has not been damaged in the process, which is quite possible if it was running on empty or while the system was clogged. Given the relatively large number of possibilities at this point however, I would probably take it to an MB mechanic and at the very least let them diagnose the issue.
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Junior Member
Joined: Feb 2019
Posts: 35
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From: Canada
ML350 Bluetec 2014
I reinstalled the pump and found there was a little bit damage on the small o-ring of the AdBlue pump, but it seems that's not really the reason for P20E8 code since the damage is only a tiny scratch. There wasn't any crystal plug. The temp. was -15 degree C that day, which may cause this o-ring damage problem.
After the re-installation, erased the code, but it came back again within a day, with roughly 2/3 of the tank filled. Then I top-off the adblue, erased the code again. Then the P20E8 has stayed off.
So far seems fine but the I/M readiness of CAT and HRT is still in red. Anyone knows what is the Drive Cycle Test of ML350 Bluetec to reach I/M readiness? Thanks guys.
After the re-installation, erased the code, but it came back again within a day, with roughly 2/3 of the tank filled. Then I top-off the adblue, erased the code again. Then the P20E8 has stayed off.
So far seems fine but the I/M readiness of CAT and HRT is still in red. Anyone knows what is the Drive Cycle Test of ML350 Bluetec to reach I/M readiness? Thanks guys.
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Posts: 35
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From: Canada
ML350 Bluetec 2014
Current status: After nearly 3000km, the P20E8 came back again. Then around 3 litres AdBlue were addded. Erased the code, seems fine. Then a new code P203D appears, which is Reductant level sensor circuit high. Will some DIYers please help identify the problem? Thanks a lot!
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W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
P203D comes up when the ECM is not getting a reading from the DEF level sender (i.e. if you've got an open circuit), which a corroded electrical connection would do. Did you by any chance overfill the tank? DEF fluid is corrosive and can easily oxidize electrical connectors, which are all on top of the AdBlue tank so overfilling it is always a bad idea. Can you get to the tank, flush the outside (top) with some water and then clean all the electrical connectors with DeoxIT?
As for the P20E8, it's very likely the same issue as before with the module inside the AdBlue tank. Now that ambient temperatures have dropped, materials shrink and/or lose their elasticity so you could have an air leak, or again, it's corroded electrical contacts somewhere along the line.
As for the P20E8, it's very likely the same issue as before with the module inside the AdBlue tank. Now that ambient temperatures have dropped, materials shrink and/or lose their elasticity so you could have an air leak, or again, it's corroded electrical contacts somewhere along the line.
Junior Member
Joined: Feb 2019
Posts: 35
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From: Canada
ML350 Bluetec 2014
Thanks, Diabolis, You are right, I did have some overfill 10 months or so before and may not clean thoroughly. I will try DeoxIT and see. Thanks. The P20E8 code seems to disappear after the refill. So if it is air leak, it may be difficult to find out the exact leaking location. Any suggestion to locate it?
Thanks.
Thanks.
Newbie
Joined: Jan 2023
Posts: 1
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2012 MZ ML350 BLUETEC
hey where can you buy the chip/emulator from i would like to get one
Hey everyone,
I get the P20B9 check engine light (Reductant Heater A Control Circuit/Open) but the suv seems to run fine. I initially thought the problem was the heater crapping out but I think it's a wiring issue since I don't get the X amount of starts left on my dash. Also, if the heater crapped out, the def would freeze in the -30C temperature we had here in Ontario.
Anyways, so I proceeded to drop the tank and accidentally broke the long/slim black nozzle on the def fluid pump (I was pissed). Do I need the change the entire pump now? Gluing the small piece back in doesn't seem possible. Anyone else with the P20B9 code that could help? A part of me wants to say ?&*( all of this crap and put the chip/emulator in and never touch the crappy SCR system ever again.
VIN = 4JGDA2EB4DA231578
Thank you in advance!
I get the P20B9 check engine light (Reductant Heater A Control Circuit/Open) but the suv seems to run fine. I initially thought the problem was the heater crapping out but I think it's a wiring issue since I don't get the X amount of starts left on my dash. Also, if the heater crapped out, the def would freeze in the -30C temperature we had here in Ontario.
Anyways, so I proceeded to drop the tank and accidentally broke the long/slim black nozzle on the def fluid pump (I was pissed). Do I need the change the entire pump now? Gluing the small piece back in doesn't seem possible. Anyone else with the P20B9 code that could help? A part of me wants to say ?&*( all of this crap and put the chip/emulator in and never touch the crappy SCR system ever again.
VIN = 4JGDA2EB4DA231578
Thank you in advance!
Thread Starter
Senior Member
Joined: Nov 2015
Posts: 275
Likes: 49
From: Ottawa, Ontario
2013 ML350 Bluetec, 1966 Ford Mustang Convertible (sold)
Newbie
Joined: Jan 2024
Posts: 1
Likes: 0
Mercedes gl350
I have the same code 20B91B and replaced the line
but the cel comes on when it gets below minus degrees.
any help would be great.
Thread Starter
Senior Member
Joined: Nov 2015
Posts: 275
Likes: 49
From: Ottawa, Ontario
2013 ML350 Bluetec, 1966 Ford Mustang Convertible (sold)
No adaptations/coding was needed for me. I only erased the CEL and it never came back.
Thread Starter
Senior Member
Joined: Nov 2015
Posts: 275
Likes: 49
From: Ottawa, Ontario
2013 ML350 Bluetec, 1966 Ford Mustang Convertible (sold)
I'm assuming your GL350 is between 2013 and 2015-2016 (X166)? This seems to be the part you need (call your dealer to make sure!):
https://www.idparts.com/diesel-exhau...4-p-15891.html
Here's a video I found on how to do it yourself:
Parts number seems to be 1664702224.
Found one on Ebay for much cheaper!
https://www.ebay.com/p/782852963
Good luck!
Newbie
Joined: Sep 2023
Posts: 6
Likes: 1
2015 GL 350 Bluetec
That's a good question! It was 5 years ago, so I unfortunately don't remember the part number. Have you tried calling your local dealership to ask them?
I'm assuming your GL350 is between 2013 and 2015-2016 (X166)? This seems to be the part you need (call your dealer to make sure!):
https://www.idparts.com/diesel-exhau...4-p-15891.html
Here's a video I found on how to do it yourself:
https://www.youtube.com/watch?v=7c69kyJN29U&t=1462s
Parts number seems to be 1664702224.
Found one on Ebay for much cheaper!
https://www.ebay.com/p/782852963
Good luck!
I'm assuming your GL350 is between 2013 and 2015-2016 (X166)? This seems to be the part you need (call your dealer to make sure!):
https://www.idparts.com/diesel-exhau...4-p-15891.html
Here's a video I found on how to do it yourself:
https://www.youtube.com/watch?v=7c69kyJN29U&t=1462s
Parts number seems to be 1664702224.
Found one on Ebay for much cheaper!
https://www.ebay.com/p/782852963
Good luck!
Newbie
Joined: Sep 2023
Posts: 6
Likes: 1
2015 GL 350 Bluetec
That's a good question! It was 5 years ago, so I unfortunately don't remember the part number. Have you tried calling your local dealership to ask them?
I'm assuming your GL350 is between 2013 and 2015-2016 (X166)? This seems to be the part you need (call your dealer to make sure!):
https://www.idparts.com/diesel-exhau...4-p-15891.html
Here's a video I found on how to do it yourself:
https://www.youtube.com/watch?v=7c69kyJN29U&t=1462s
Parts number seems to be 1664702224.
Found one on Ebay for much cheaper!
https://www.ebay.com/p/782852963
Good luck!
I'm assuming your GL350 is between 2013 and 2015-2016 (X166)? This seems to be the part you need (call your dealer to make sure!):
https://www.idparts.com/diesel-exhau...4-p-15891.html
Here's a video I found on how to do it yourself:
https://www.youtube.com/watch?v=7c69kyJN29U&t=1462s
Parts number seems to be 1664702224.
Found one on Ebay for much cheaper!
https://www.ebay.com/p/782852963
Good luck!
Thread Starter
Senior Member
Joined: Nov 2015
Posts: 275
Likes: 49
From: Ottawa, Ontario
2013 ML350 Bluetec, 1966 Ford Mustang Convertible (sold)
Wish I could help you more.
Good luck! Keep us posted how it went.
