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2011 ML350 BT adblue system code 20E821 + discrepancies
There are a couple of threads on the Adblue system, a lot of which deals with trying to get Mercedes to fix the problem. I see discrepancies in the error codes. My icarsoft i980 gives two codes; 20E821 and 823. Both say "The pressure in the Adblue system is too low." What does this indicate? In one thread a user listed this code as low fuel pressure. VIN 4JGBB2FB6BA733038. Location Alabama, US, Thanks
Last edited by frederickcarney; 04-25-2018 at 09:29 AM.
Reason: added VIN
Thanks for the suggestions, I added VIN number to top post. I'm tentatively ruling out #2 and #4. The original owner always serviced at Mercedes dealer and used MB brand. I lifted up the floor board and there is not a hint of any urea ever spilled. I know you are talking about the inside but this suggests being careful with the fluid. As far as I'm concerned any name brand is same-same. All DEF made to ISO standard with deionized water. The weather here is warm now, 70's daytime, 50's night.
Thanks for the suggestions, I added VIN number to top post. I'm tentatively ruling out #2 and #4. The original owner always serviced at Mercedes dealer and used MB brand. I lifted up the floor board and there is not a hint of any urea ever spilled. I know you are talking about the inside but this suggests being careful with the fluid. As far as I'm concerned any name brand is same-same. All DEF made to ISO standard with deionized water. The weather here is warm now, 70's daytime, 50's night.
Where are you located? Can you put that in your profile also, please?
Dealer service does not rule out corrosion, because moisture can accumulate between services if the reservoir runs low, or for other reasons. But it isn't common, from what I can see. My experience with diesels is very limited. I would have the pump checked (AdBlue needs to be injected at a specific pressure, the number 25 psi seems to come up in other threads) but for further insight Maj. Dundee probably needs to jump in.
Yes, I did have a check engine light. That is when I used the i980 reader to see the error codes. I reset the error code drove around for a while, made a few stops, then the light came back on again. I got the same error code again, 20E821.
Does anyone know if the pump only is replaceable? Given the mileage, no matter what the specific problem is, wouldn't it be better to put another complete unit in (rebuilt)?
Does anyone know if the pump only is replaceable? Given the mileage, no matter what the specific problem is, wouldn't it be better to put another complete unit in (rebuilt)?
I took the vehicle to one of the top repair shops in the area and they said that the pump does need replacing. I can't find anything specific on replacing the pump here or on youtube videos. It looks to be an easy repair. Is this a simple DIY repair? Are there any tricks to know? Does the pump need to be filled when installing? I assume that I will get an error code when I disconnect the old pump so just clear it out when finished? Thanks
I think the pump is attached to the AdBlue tank with three nuts. The bad news is that to get to it you have to drop the entire tank. The good news is that the instructions to change the heater require you to remove the pump so you can probably use that for DIY. It doesn't seem like a major job, but as I said, my diesel experience is almost non-existent so take this with a grain of salt and approach with caution.
04-24-2018, 06:43 PM
