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So a I got CEL showing code P0441 Evap Emission Control System Incorrect Purge Flow in my W204 last week. I’ve read tons of posts about it but none answer my specific question. Long story short, I took it to the dealer and they ran their “fancier” diagnostic tools and came back with this recommendation:
“Purge line with check valve faulty, part #271-018-02-00, recommend replacing and performing software update to engine control unit (Evaporative emissions fault)”
They quoted me $500 to replace it. My question is, does anyone know where this part is located in the evap system? I searched the part number but all that comes up is the name “purge line” and that its around $45. I can’t find any pictures or schematics showing what it looks like or telling me where its located. If its easy to access I’d rather change myself to save me the stealer’s fee.
So a I got CEL showing code P0441 Evap Emission Control System Incorrect Purge Flow in my W204 last week. I’ve read tons of posts about it but none answer my specific question. Long story short, I took it to the dealer and they ran their “fancier” diagnostic tools and came back with this recommendation:
“Purge line with check valve faulty, part #271-018-02-00, recommend replacing and performing software update to engine control unit (Evaporative emissions fault)”
They quoted me $500 to replace it. My question is, does anyone know where this part is located in the evap system? I searched the part number but all that comes up is the name “purge line” and that its around $45. I can’t find any pictures or schematics showing what it looks like or telling me where its located. If its easy to access I’d rather change myself to save me the stealer’s fee.
Appreciate any help! Thanks MBWorld
I currently have the same issue. Hoping someone in MBworld can answer this.
Rcampos sorry to hear you’re in the same boat. Maybe we can help each other. Do you happen to hear a faint puttering when your engine turns over during ignition? I noticed one coming from either the engine compartment or underneath the car I think. I need to spend some time this weekend pinpointing the exact location, but i think it might be related to the “purge line”. It almost sounds like it could be pressure excaping from a loose or damaged hose.
I’ll let you know if I find anything. I also ordered the part the dealer specified from ebay since it wasn’t very expensive. If anything, having it will answer the question of what it looks like, and if it turns out to be inaccessible then at least I will have the part on-hand when I take it to a shop for the fix.
Rcampos sorry to hear you’re in the same boat. Maybe we can help each other. Do you happen to hear a faint puttering when your engine turns over during ignition? I noticed one coming from either the engine compartment or underneath the car I think. I need to spend some time this weekend pinpointing the exact location, but i think it might be related to the “purge line”. It almost sounds like it could be pressure excaping from a loose or damaged hose.
I’ll let you know if I find anything. I also ordered the part the dealer specified from ebay since it wasn’t very expensive. If anything, having it will answer the question of what it looks like, and if it turns out to be inaccessible then at least I will have the part on-hand when I take it to a shop for the fix.
I do have a faint puttering when I start the car. I also found a small plastic broken hose. This small hose is near the air intake pipe. I replaced with hose but now I’m not building any boost. Hoping all of this is related.
I do have a faint puttering when I start the car. I also found a small plastic broken hose. This small hose is near the air intake pipe. I replaced with hose but now I’m not building any boost. Hoping all of this is related.
Did the puttering noise go away when you replaced the hose? What exactly do you mean when you say “not building any boost”? I didn’t get to spend some time today to work on my car, but I’ll check out all the hoses near the air intake when I have time tomorrow. Thanks for giving me a place to start my search.
The noise did go away after I replaced the hose. But now when I drive the car I feel that the turbo doesn’t build any boost. Basically I have a lost in power but not sure if it’s related. I will dig deeper today to see if I’m having any physical issues with the turbo.
The noise did go away after I replaced the hose. But now when I drive the car I feel that the turbo doesn’t build any boost. Basically I have a lost in power but not sure if it’s related. I will dig deeper today to see if I’m having any physical issues with the turbo.
That’s great that the noise went away. Did you verify if the P0441 code cleared after replacing the hose? Good luck troubleshooting the turbo.
Update: I spent a few hours on Sunday poking around the engine to check hoses and try to pinpoint the source of the "puttering". Didn't find any damaged or loose hose, but the "puttering" noise turned out to be coming from the engine itself. After some research, I found this video on youtube that sounds exactly like the noise. (
) My engine progressively worsened from a puttering to a full on rattle at startup in the last few weeks. From what I've read, the sound can be related to the camshaft adjusters which apparently is a known issue with the M271 engine. So at this point, I've gone down the rabbit hole of camshaft adjusters, timing chain, etc as the potential cause of the noise. I'm struggling to see how a simple purge line could be in anyway related to it. There was a theory in another forum post that said engine rattle could be caused by fuel getting into the engine oil. Perhaps there's a connection to this "purge line" and allowing that to happen.
Update 2: I found the "purge line". I ordered the part number that the dealer reference on their findings report (271-018-02-00) and it arrived on Weds. This was a big help. I took a good look at it and went hunting in my engine compartment. It turns out that this part is the second hose section after the evap system purge valve. It attaches to a 90° rubber connector (upstream), then wraps underneath the intake manifold and out of sight. It has a check valve at the other end (downstream) which plugs into the engine block and then another connection point for another hose to attach to the body of the check valve. Looking at the photos below should help if my description sucks.
I tried for a good hour to swap the new one in from the top side, but I didn't get anywhere. Since I couldn't see the check valve side, I was basically working by feel, and wasn't able to get it unscrewed. I think it will probably be easier to work from underneath the car with the splash shields removed. I have an appointment for a lift bay at a DIY garage tomorrow morning. I'm going to try and swap it out from underneath the car, do an oil change, and pray that it helps eliminate the rattle on startup.
Would love some pointers for anyone who's done it before. Not much turned up on youtube and previous posts about this particular part or swapping it out.
View from top showing mystery purge line from dealer service report.
Closeup of top of purge line
Picture from underside of manifold showing where it connects to. This is out of view from the top. I had to reach my iPhone down in there to take the picture.
Here's the new part that came in. I'm holding it upside down from how its actually installed in the car. Check valve front Check valve back showing connection Part number shown
I just worked on a 2012 C250 with the same issue. The vehicle kept throwing a P0441, but with no freeze-frame data available. The gas cap seal tested fine. At a glance, the FTP sensor responded normally during purge duty cycles. We replaced the Purge Solenoid assembly with a Genuine MB unit and the issue went away for a short period of time. Thanks to this thread, we became aware of a check valve in the purge line assembly.
The Purge Line Assembly is bolted to the underside of the intake manifold. Unfortunately, there is very little clearance between the bottom of the intake manifold and the A/C compressor; the purge line is bolted to the intake manifold using a T25 fastener. So, you have two options - a) remove the intake manifold assembly or b) remove the throttle body, drive belt and unbolt the a/c compressor (with the lines attached). I chose the latter; keep in mind that two of the a/c compressor's E12 bolts are best accessed thru the driver-side wheel well using a variety of wobble extensions.
I think the purpose of the check valve is to prevent boost pressure from going the other direction (i.e. back towards the fuel tank). I blew into the portion of the purge line that connects to the intake manifold, and the old one allowed air to go right out to the purge solenoid connection. The new one did not. So, I am fairly confident that the old purge line assembly on this car was bad.
Also, I checked for a ME update using our Autel's server (not sure how updated this is) and it appeared that this particular vehicle was already up-to-date.
Hope this helps.
Disassembly required to gain access.
No update was available.
Last edited by The Critic; Jan 8, 2019 at 02:15 PM.
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