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Thread: P0441 Evap Emission Control System Incorrect Purge Flow

  1. #1
    Junior Member
    Join Date
    Jan 2005

    P0441 Evap Emission Control System Incorrect Purge Flow

    The Check Engine Light of my C220 has come on. She has done a little over 1,00,000 miles...
    I took to AZ and got a diagnostic done. It read "P0441 Evaporative Emission Control System Incorrect Purge Flow".
    Can anybody help in diagnosing wots causing it...??
    I hv chkd the gas seems to be fine and shut tight...

    96 C220

  2. #2
    Moderator Pagz's Avatar
    Join Date
    Oct 2004
    New Zealand
    I may be wrong but.....,that system consists of a pipe running from you tank,through to your engine bay,through a solinoid,then a non-return valve...then up to the throttle body....
    the system draws any vapour from the tank via vaccum from the throttle body...

    Maybe the non-return or the solinoid is faulty??.....
    hope this helps alittle...

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  3. #3
    DTC code P0441 is almost always a faulty evap purge valve(regeneration valve in MB literature). It is very common for this model and the valve sits on the frame rail on the left front fender right next to the washer tank. It is a black solenoid valve that has two large vacuum lines going to it on each side and in white lettering it will say "MOT" with an arrow indicating flow. When they are woorking properly they "pulse" and are somewhat noisy, like a ticking sound. When they fail they usually stick closed and don't allow the evap pressures from the tank to release into the intake manifold. The valve is fairly cheap and take about 3 seconds to replace.

  4. #4
    Senior Member
    Join Date
    Dec 2002
    713 should also check that pipe. I forget what it was. The one that leads from the EGR to the engine block? Damn, do a search it's in here somewhere. That pipe can have carbon build up and reaming it out or replacing it with the updated part usually helps.
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  5. #5
    A clogged EGR tube would give codes for EGR faults, not for evap flow malfunction.

  6. #6
    Junior Member
    Join Date
    Jan 2005
    Whats the EGR..??
    Offlate I have been experiencing a couple of other problems...
    The brakes tend to grab when coming to a stop...the engine also surges for a second...or two...the brakes act funny only at very low speeds or when coming to a stop....
    The engine emanates a knocking sound when I rev up in park or neutral or accelerate in drive...for a very short time....I dont hear that sound when I'm normally cruising....The sound is more like that of a worn connecting or crankshaft bearing....But then if thats the case shouldn't it be constant...the engine runs smooth when cruising normally...even at higher speeds.....The sound comes for a very short time...
    The transmission tends to hesitate a bit before changing gears..
    Would adding a bottle of Trans-X help..??

    96 C220

  7. #7
    EGR is Exhaust Gas Recirculation. It is an emissions system that directs exhaust gas through a tube to your intake manifold at cruising speed to help reduce emmisions, unfortunately the tube diameter is fairly small and after time/mileage it cloggs with soot and gunk which can cause a check engine light for EGR malfunction. That is not the case as you described with your car, at least for now, lol.

    Your brake problem seems odd, would most likely need to drive it to fully understand your complaint.

    For the engine noise, check your belt shock bushing at the top. It's a long black shock(about 6in.) that sits just to the driver's side of the valve cover. It helps reduce belt tension fluctuations and it is very common for the bushing to wear and make a knocking sound. It can easily be mistaken for a lower engine noise. Just put your finger on the end of the shock wiith the car at idle and see if the noise gets better.

    For your transmission, I would recommend having it serviced if you haven't lately, but I would stay away from fluid additives. Just my opinion.

  8. #8
    Junior Member
    Join Date
    Jan 2005
    I had replaced the Belt shock and the tensioner recently.
    Also the sound does not come when the engine is comes when you rev up the engine....comes for a short time and as you rev higher dissapears...And when you rev it up a bit more the engine starts missing as if one of the cylinders not firing...
    The noise is something thats baffling me...
    It does not come up when going at steady speed...even when cruising at 80 mph...
    Any suggestions would be highly appreciated..

  9. #9
    Junior Member
    Join Date
    Jan 2005
    I looked around for the Purge valve...
    Could not find it... Next to the w/s washer reservior all I could see is the ABS pump... The ABS pump does not tick or feel like it working even with the engine running... Is this how it is supposed to be..???
    Does the ABS start working when u slam on the brakes..?
    Is the purge valve under the w/s reservior...??
    96 C220

  10. #10
    Junior Member
    Join Date
    Jan 2005

    I finally found the Purge valve...
    I checked the purge valve....found that the terminals were corroded...
    I cleaned the terminals...chkd the voltage at the connector..( 11.75 V)
    Connected and checked again...Now with the switch turned on w/o the engine started the purge valve was not operational even though there was voltage at the connectors. I started the engine and after sometime the purge valve started ticking... I shut the engine...restarted...same...The purge valve started working after some time....Is this how it suposed to be...?
    Or should it start working the moment you switch on the ignition?
    Now that the purge valve started working I went about resetting the Check Engine Light.... Tried AZ...they said they cannot...So disconnected the battery for a couple of mins...and lo and behold...the CEL was reset..
    Drove the car for an hour...The light hasn't come up yet...
    If the fault still exists how long would it take for the CEL to come on again..??

  11. #11
    hey, how'z the purge valve working out for u? i'm haveing the same problem. i actually went over a curb ont eh left front at 50mph. since then the engine revs up and down when i come to a stop. i'm getting p1444 and p0441. i checked the lines fromt eh carbon canister to the engine, all look good. where is the purge valve?
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  12. #12
    Senior Member
    Join Date
    Nov 2004
    purge valve is the one labeled MOT and is located at the base of the washer fluid reservoir.

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  13. #13

    Thanks for helping me, maybe this will help too.

    Benzaddict, thanks for the accurate advice.

    This is the third or fourth time I've gotten some excellent advice from I always try to reciprocate by sharing whatever knowledge I gained, so here it is FWIW.

    I had codes p1170 (short term fuel trim )and P0441 EVAP function. I observed that the car ran like crap, seeming slow, and stumbing at idle. My wife told me it was getting far less then its typical gas milage. ( This is anecdotal, as I didnt observe it, but I believe her. )

    Checked the evap valve or "regeneration" just as you described and found that it was open continually.

    It had 12v but wouldnt close. I tried connecting across the battery directly but it still wouldnt close. I measured the valve coil and found 46 ohms. That would be only a 1/4 amp draw.

    I pried off the cap to find a simple needle/seat combo that relies on coil current to draw in the "needle" to close the valve.

    Then checked Mercedes Benz of Orlando, they said they had to order it for $140. My best price online was benzbin @ $117.00 ( these are US dollars btw )

    3 beers later I had plugged the intake pipe to the engine , made a cotton filter for the two lines leading rearward to the fuel cell, and told the wife the engine light would just stay on. I scan it from time to time anyway. The weak performance and stumbling idle is gone now and it runs as well as it ever has.

    Thanks buddy! Car's back on the road, wife is happy, I spent nothing.

    If there is a downside to this except for a little fuel vapour in the atmosphere, feel free to let me know. From here it seems like the end of the issue.

    Thanks again for helping people you will never meet.
    1994 C280, my own private hell.

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