P0442 evap system small leak on 2015 ML 350

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Oct 23, 2025 | 09:44 AM
  #1  
Good Morning,

I got P0442 evap system small leak check engine light, so far, clean the gas cap and surrounding, drives few days. and the code is still remain, so I went ahead to order replacement gas cap. start drive and code still remains, do I have to clear the code or just start to drive to see what happened? Guess my next step if code is still remain is located where is the purge valve under the hood, I don't know where is it located under hood? of course I know there is a lots of possibilities, few pipes and connection and canister valve area. Attached is the photo of under hood, please anyone can help to identify where is it? also anyone can give me some advice or ideas?

Thanks so much
Frank

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Oct 23, 2025 | 12:01 PM
  #2  
just found where is the purge valve is on my 2015 ML 350 , the part number is OEM 0014760532 Vapor Canister Purge Valve for Mercedes-Benz, and there is earlier part #000-476-06-00 and 000-476-06-00-64 were back order in some MB site, and I found one at https://www.pelicanparts.com/ for $57. Attached is the location under the hood. I will update everyone once I replace it.

Frank

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Oct 23, 2025 | 02:19 PM
  #3  
Great news, after I wrote the previous post. I went for Grocery , it is about 4 miles drive with the code. and when I on the way home, after drive for 2 min, I just realized the code is gone. So I figured the ECM has time, or miles to drive to start check eval system. I am so happy that is the root cause of it, and the one I got one from amazon cost only $12, at
Amazon Amazon
, i also think after I cleaned the old cap, and took few days and the code is still there. that make perfect sense the ecm only take less then one day to see it is fix or not.

Thanks

Frank
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Oct 27, 2025 | 08:15 AM
  #4  
Patience is the key fix to P0442 / P0456 codes
Quote: Good Morning,

I got P0442 evap system small leak check engine light, so far, clean the gas cap and surrounding, drives few days. and the code is still remain, so I went ahead to order replacement gas cap. start drive and code still remains, do I have to clear the code or just start to drive to see what happened? Guess my next step if code is still remain is located where is the purge valve under the hood, I don't know where is it located under hood? of course I know there is a lots of possibilities, few pipes and connection and canister valve area. Attached is the photo of under hood, please anyone can help to identify where is it? also anyone can give me some advice or ideas?

Thanks so much
Frank
These codes have plagued the auto industry for a long time. More often than not they DON’T reflect an engine condition, yet they light the Check Engine warning light anyway. Even then there’s no way to verify that action taken was effective. After having this code show up five times in two years on two vehicles (one only a week old!) I suggest ignoring it for AT LEAST six months (!) or 400 miles after action has been taken (!).
The codes showed up on my 2013 ML350 five minutes after refueling. I waited two weeks, then replaced the gas cap, cleared both codes (but not the “permanent” codes) and drove to New England (600+ miles RT) for a week’s vacation. I was convinced it was just the gas cap. But the new cap changed nothing, so I put back the original when I refueled mid-trip and drove home. When I refueled after returning, the codes all vanished. There was NO problem at all. Second car, a 2023 GV70, took the dealer three 1-week maintenance visits over a 2-year period to resolve. No problem there, either. Ultimately resulted in a recall for software on this vehicle.
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