P0440 Code - keeps coming back
Thread Starter
MBWorld Fanatic!
Joined: Aug 2014
Posts: 1,060
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From: Montreal, QC
E55 AMG & C63 AMG
P0440 Code - keeps coming back
I've changed out:
- Fuel cap
- Purge Valve on driver's side
Every week I get a CEL... I scan and it comes out as 'P0440 Evaporative Emission System'
Clear it and it comes back a week later. Getting a little redundant.
What else could it be? Cracked lines maybe running to the purge valve? I read something about a charcoal canister?
Are there any negative effects if I run the car with this Evap Code always pending?
Thanks in advance.
- Fuel cap
- Purge Valve on driver's side
Every week I get a CEL... I scan and it comes out as 'P0440 Evaporative Emission System'
Clear it and it comes back a week later. Getting a little redundant.
What else could it be? Cracked lines maybe running to the purge valve? I read something about a charcoal canister?
Are there any negative effects if I run the car with this Evap Code always pending?
Thanks in advance.
Thread Starter
MBWorld Fanatic!
Joined: Aug 2014
Posts: 1,060
Likes: 98
From: Montreal, QC
E55 AMG & C63 AMG
How do I access the Charcoal Cannister? Anyone have a DIY?
Last edited by MTV10; Jan 25, 2016 at 08:38 PM.
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MBWorld Fanatic!
Joined: Dec 2011
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Mercedes
Fill tank to the brim, drive around a minute, and then sniff if there's fumes. If even a little stink, the dealer should handle it. The evap problem may have come from the dealers repairs. I am having continual evap codes ever since the dealer did my scam repair.
MBWorld Fanatic!
Joined: Oct 2012
Posts: 1,242
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From: Canada
2004 E55 AMG
not sure if you've already read similar threads but alot of old E55 owners were suffering through this problem.
2 years back I took my car into dealership and what they did was a software upgrade and on the invoice it said
"AMG raised the emission threshold" since then the light didn't come on. Can't remember the exact words but that's what they did.
2 years back I took my car into dealership and what they did was a software upgrade and on the invoice it said
"AMG raised the emission threshold" since then the light didn't come on. Can't remember the exact words but that's what they did.
Newbie
Joined: May 2015
Posts: 3
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2005 ML350 Special Edition
The easiest test, in my opinion, would be to smoke test the EVAP system. Especially since it's a code that keeps coming back. Majority of the EVAP leaks that I've diagnosed on 211s were coming from the valve on the charcoal canister. But to correctly diagnose that, you'd need the computer at the dealership to shut the valve. What I've seen is that the valve still leaks even after the valve is shut, which triggers the EVAP leak code 
hope that helps!
hope that helps!
MBWorld Fanatic!
Joined: Jul 2014
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From: Earth, USA, Atlanta, GA
E55
I'm not sure why it's so hard to understand this...I've told you before and I'll tell you again. A dealership replaced the fuel tank, therefor touching the EVAP components. You now have codes popping up regarding the components and now they are throwing error codes and CEL's. Get them to diag the issue and fix it. They will find out in 20 minutes what you will find out in 2 weeks of clearing codes in your garage and shaking your head
MBWorld Fanatic!
Joined: Oct 2012
Posts: 1,242
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From: Canada
2004 E55 AMG
I'm not sure why it's so hard to understand this...I've told you before and I'll tell you again. A dealership replaced the fuel tank, therefor touching the EVAP components. You now have codes popping up regarding the components and now they are throwing error codes and CEL's. Get them to diag the issue and fix it. They will find out in 20 minutes what you will find out in 2 weeks of clearing codes in your garage and shaking your head
So he's trying to avoid additional costs. For me diagnosis is 200$
They've done it for free sometimes cuz I know the foreman
or cuz I was nice lol 
That's what I think but we'll find out more once OP posts again
Thread Starter
MBWorld Fanatic!
Joined: Aug 2014
Posts: 1,060
Likes: 98
From: Montreal, QC
E55 AMG & C63 AMG
I'm not sure why it's so hard to understand this...I've told you before and I'll tell you again. A dealership replaced the fuel tank, therefor touching the EVAP components. You now have codes popping up regarding the components and now they are throwing error codes and CEL's. Get them to diag the issue and fix it. They will find out in 20 minutes what you will find out in 2 weeks of clearing codes in your garage and shaking your head
2. My fuel pumps / sending units were
3. This code was happening before the dealer even warrantied my car....
I can try and bring it into dealer to check.. but their rates are stupid and I refuse to support outrageous labour costs.
MBWorld Fanatic!
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From: Earth, USA, Atlanta, GA
E55
MBWorld Fanatic!
Joined: Nov 2014
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E55
pay the rate. it will be much cheaper than spending hours of your time and throwing parts at it. thats why the rates are what they are because they have the proper equipment and knowledge to test and diagnose the system.
Super Member
Joined: Dec 2007
Posts: 846
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From: ATL
2017 GLS 550
for evap type issues I will take it to dealer to get diagnoses. If you get a good service writer he will give you a list of everything they recommend replacing. then you can do the work yourself.
MBWorld Fanatic!
Joined: Oct 2012
Posts: 1,242
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From: Canada
2004 E55 AMG
Why would he warranty your car -if there is a pre-existing code related to this specific fuel related issue ?
Maybe we both are talking about something else and which is causing this confusion.
Do you know that US cars have extended warranty now on their fuel leaking issue ?
Is your car under warranty for that specific issue as well? if yes (how did you get that) and get it fix under the warranty -if not- get it diagnoses instead of buying parts.
Secondly, like I said before- I had a similar issue -they plugged the car in and they saw there was an update -Update was "AMG increased the evap thresholds" or similar thing like that.
Good luck
Junior Member
Joined: Mar 2015
Posts: 52
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2012 CLS63 & E39 M5
I have encountered this same issue. I have gotten the fuel tank, sending units , and what ever else goes with the tank replaced about a year ago. And this is the first time since then that I have had an issue. The 1st time it came up I got a red warning on the instrument cluster saying that my gas cap was off or not tight when it was on securely. I took it to autozone and had them flash it. Was good for about 100 miles and now is back. Has anyone actually resolved this issue with any success?????
Junior Member
Joined: Jul 2014
Posts: 64
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soon to be '04 e55
I had the gas cap warning light for about a month, I check and looked for possible leaks, did hours of Google research, I finally had one thing that it pointed to. The charcoal canister purge valve, which mercedes updated and requires a pigtail. Parts were at my door in less than a week and installed the very same day. That was over 6 months ago and no more lights or codes.
Junior Member
Joined: Jan 2015
Posts: 56
Likes: 0
2006 MB E55 AMG
I had the gas cap warning light for about a month, I check and looked for possible leaks, did hours of Google research, I finally had one thing that it pointed to. The charcoal canister purge valve, which mercedes updated and requires a pigtail. Parts were at my door in less than a week and installed the very same day. That was over 6 months ago and no more lights or codes.
Junior Member
Joined: Mar 2015
Posts: 52
Likes: 2
2012 CLS63 & E39 M5
