I've had numerous issues with my 1997 E420 (90,000 miles). I recently replaced the intake manifold (drivers side was leaking) and replaced the catilytic converter on the passenger side (plugged, likely from the intake leak leaning out half my engine and making the other half too rich?).

I'm down to one nagging and apparently common problem: P0455 large evap leak.

I get all the common faults (the check engine light is always on and sometimes I get the flashing low fuel light when I'm stopped at a traffic light). The car sees to run fine but I would like to fix this last annoying glitch.

It is not my gas cap, so I'm assuming that the charcoal cannister or the purge valve is the problem, or possibly a failed vacuum line in the purge system?

So, finally, my question: Can someone offer some sugestions how to narrow down the problem? And, where are the charcoal canister and purge valve located? I'm leaning towards just buying a purge valve and swapping it out. I ahve used the search button to get this far, but I do not know what the purge valve looks like, or even where they are typically mounted.

P.S. I'm an experienced mechanic but a Mercedes imibicile as of today.

Thanks in advance for any help.

while pursuing the P0455 code on my '97 E320 was to 1) put a good squirt of WD40 into the side of the purge valve which has the line running to the rear of the car and 2) removing the rubber gasket from under the fuel filler cap and flipping it over. So far code has not come back. Seems more likely that the WD40 is the reason but the flashing fuel guage light is supposed to indicate a leaky or missing fuel filler cap. I'm not 100% convinced that the problem is cured but I have over 500 miles added since these "fixes" and no codes or flashing fuel guage lights. FWIW.

Is the purge valve the little valve located on the drivers side of the car on the side of the ABS brake device? P/N 000 470 2093?

I just bought a new gas cap, I'm going to see how the solenoid sounds when I put 12VDC on it.

On my 98 C230, I have spent a lot of energy (and money) solving this problem. first, the purge valve failed. Solved that, and then a couple months later the fuel sensor went out (yes, the fuel level sensors are part of the evap system) so I replaced them. Problem solved for some months until the cannister finally went too.

Then, about three months ago, the problem came back. This time all compenents tested okay, but the SDS indicated "electrical failure." We cleared the CEL and I decided to leave it alone and wait until time and budget allowed for tracing this new screw up. Well, the CEL never came back and the fuel light no longer blinks. A one-time glitch? Let's hope so.

You can check the operation of each component using SDS.

__________________
John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

Well my purge valve appears to be fine, it operates properly when I apply 12 volts, and with a 'bit' of air pressure on the tank line it is apparent there is no 'gross' leak.

Can someone tell me where the charcoal canister is on an E420?

behind the right rear wheel under the arch covering.

__________________
David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

Thanks, I'll check that today.

Hi,
I have the 1997 s420 and I added some marvel mystery additive to the fuel and once the tank reached 3/4 the low fuel light started to blink and eventually the CEL came on with a code p0455. I did some basic tests like vucum check on all the lines in the purge system including Charcoil canister and fuel tank and every component holds vacum. Any help is appreciated.
thank you.

why don't you try treating the purge valve with WD40 as I described above. I've been running without P0455 error for 9 months since I did.

My problem was finally traced to a leaking intake gasket. I could hear a sucking sound and sure enough the intake on one bank was sucking a LOT of air.

As a result, the engine richened the mixture, which made the other half of the engine way too rich, so my catalytic converter was messed up also.

So, new intake gasket, punch out the converter (yes, it still passed emissions easily) and my prblems are solved.