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-   -   2004 E320 wagon fuel leak leads to P0446 and P0171 faults after changing fuel filter (https://mbworld.org/forums/e-class-w211/742417-2004-e320-wagon-fuel-leak-leads-p0446-p0171-faults-after-changing-fuel-filter.html)

Douglas Kerr 04-20-2019 10:00 PM

2004 E320 wagon fuel leak leads to P0446 and P0171 faults after changing fuel filter
First off, I am new to the forum- I have been reading for awhile, but not posting. So if I have posted in the wrong place, or done something wrong here- I apologize up front.

I had fuel leaking onto the top of the tank through a crack in the top of my fuel filter and creating a gas smell in the cabin. I replaced the fuel filter. Unfortunately, the wiring harness in the car did not mate up to the connector on the top of the fuel filter, but I learned that there was a change in connectors and got an adapter from MB and all seemed fine- the car ran well and the leak was fixed.

But after a few drives I got a p0446 fault "Evaporative Emission Control System Vent Control Circuit Malfunction" error. I read on this forum that this code is typically associated with air in the fuel system or the Charcoal Canister Shutoff valve, but I felt sure that the code was related to my work and could not see how a shutoff valve would now be bad. So I went back and checked all of the electrical connectors that I had plugged and checked that I had not created any vacuum leaks in the system and to the best of my ability, I cannot find any leaks or loose connections. Then I assumed that there was air in the fuel system from the work I had done and cleared the faults. I have done this for several fault cycles and the faults would go away for several days, but then the fault would return.

Yesterday, I got a new fault p0171 telling me that the fuel is too lean. The gas is now down to about a 1/4 of a tank.

I have since learned that this issue may have been covered by an extended warranty, but I think this is a moot point now as I have corrected the gas smell in the cabin.
Any guesses as to what may be going on and where to start diagnosis? Is it possible that I got the wrong fuel pressure sensor in the filter I bought, as the electrical connectors did not match? I believe that the activation of the shut off valve in the charcoal canister is related to the fuel pressure sensor- is that correct? Could it have something to do with the fuel pressure senor, as it was part of what was replaced with the filter? I am a bit out of my depth- so thank you to anybody that can provide any input.

mericok 04-23-2019 10:31 AM

If you have 2004 W211 it has already under warranty just fuel tank leak. Mine was changed 2 weeks ago under warranty. You need to go to the MB service ASAP.

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