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MAVA needs help with a P0455 "gas cap code" or "flashing reserve fuel light"

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#1 · (Edited)
MAVA needs help with a P0455 "gas cap code" or "flashing reserve fuel light"

My beater 98 S500 runs like a champ, but I'm finally addressing the "flashing reserve fuel light" which leads to a check engine light as I cannot pass the Union of Kalifornia Emissions test with a check engine light, and my problem is wayyyyy deeeeepeerrr than the "gas cap"

I'm am trying to find a drawing showing the plumbing of the fuel tank as the problem is a passive problem, and I am so glad I have two of these cars..

On my working 96 S320 (with battery disconnected), I can hear the "swooosh" sound when I remove the fuel cap outside the car, and five to ten minutes later I can get the swoooosh again by removing the gas cap on the non moving(battery disconnected ) S320 laying in 80 to 90 degree sun, so what gives with the S500 :frown

A) I have checked my engine vacuum plumbing on the S500, and all is okay...

B) MOT Electric valve works electrically, and while energized the vacuum MOT check valve works. The plumbing on the MOT is nice and cinched-up.

C) The Charcoal Canister Purge valve is working great. When energized it blocks the release of the off-gassing of the Charcoal Canister, yet I would think the logic operation of this Purge valve would be reversed per what I encountered on the S320.

D) I removed the charcoal canister for any ruptures, or cracks, and I even blew into the big nipple where the purge valve attaches, and no leaks :crying
While doing all of this I replaced the one-time use hose clamp, and used a reusable hose clamp...

E) Yea, I did the swap of the gas cap with my E320, no change, no swooosh :crying. My S320 is not near me, so drove to it yesterday, and swapped gas caps and waited 15 or so minutes. The S320 did the swooosh, and the S500 Nothing :crying

F) The last item per the list is the "Pressure sensor/ fuel gauge sending unit" I swap the S500 sending unit with the S320, and S320 to the S500... I get the swooosh on the S320(15 minutes later) :crying:crying (I was hoping that was it), and on the S500 I get nothing(15 minutes later) :crying

Back to square one as I cannot see the fault. The tanks are not rusty visually, so like in the beginning I like to see if the tank has any other lines other than the bottom feed to the fuel pump and the fuel neck..

All of this does not matter if the car is on, and the battery disconnected....

Helpppppp...

Thank you,

Martin
 
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#2 ·
No Swoosh

Just a guess, but I'd examine the fuel return connection in the filler neck. :nerd

Everything else in the fuel line system is sealed well. Seems I read where the hose ages and cracks. I think you can access the hose after removing the trunk side panel.
 
#4 ·
Just a guess, but I'd examine the fuel return connection in the filler neck. :nerd

Everything else in the fuel line system is sealed well. Seems I read where the hose ages and cracks. I think you can access the hose after removing the trunk side panel.

I will check that area as I did not know where the return is at....

Thank you,

Martin

Do you happen to know what the associated Mercedes DTC is for the gas cap? Since the Mercedes docs don't use the "P" codes it's hard for me to find the associated solutions that are usually offered up in the docs. I suspect the code is a bit too generic.
I did not bother to know what they were in HHT, but all I cared was to reset them, yet i will get what the codes are.

I did pull the OBD codes

DTC

B1491
B1992
B2427
P0125
P0455
P0736
P1107
P1198
P1299

I will see what I get in HHT...

Martin
 
#6 · (Edited)
I get the P0455 with Xentry using the 38 pin connector. Here are my results of this morning...:frown

Martin


PS.. On a side note, The return line does not come to the neck of the tank(actually nothing comes to the neck)I. going to take a peek under the car, but I will go to the junk yard and play doctor possibly tomorrow.
 

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#5 ·
I had the same problem in my leather 1998 S420 and it took replacement of the fuel gauge sender to sort it out. That was due (I believe) the a failure of the pressure sensor on the fuel gauge sender.

Just like you, I had chased this problem all the way through the system and that was the last thing left. MOT, charcoal canister valve, etc., all checked out, everything all the way back to the tank.

There's no test for the gauge sender pressure sensor that I could find.

Dan
 
#7 ·
Ahh, actually, the PDF gave my answer. You have an ME fuel injection, not LH injection, the ME1RE gave that away and ME has the "P" codes in the docs! Same docs I'm looking at are right here: STAR TekInfo

Anyway, the official explanation says that a P0455 indicates at least two faults: "EVAP system, large leak. Fuel tank press. sensor (B4/3)"

You're not getting a P0450 which would indicate a fuel tank pressure sensor fault, but in the Trouble Code Description doc under item number 17 there is a note that says "With defective fuel tank pressure sensor, DTC P0455 is displayed."

Might be your answer, there are more suggestions in page 23/1 under item 33 and 35, but those are based on multi-meter tests with a module breakout box (although I have found much of the same info when using "actual values" in HHT, occasionally, not always).

Hope this all helps, this is exactly what I'd be doing on my car.
 
#13 · (Edited)
Dan,

No problem. Man I pulled some my self. No Hard feeling-Each one teach one here...

I think I found my problem, but I need to find out how this tank comes out, or how is the plumbing of the vent and the return. Any diagrams of what this tank looks like from the front? I hate those cheapy clamps as they loose their strength over time-My brothers 100,000 mile GM had those all over, and his cooling system could not pressurize due to hoses leaking underneath because the clamps got weak....Coolant was dripping just a little bit from about half his hoses because of those clamps....

From the picture of the two hoses. the wet one and dry one. The wet one is wet because of oil coming from the half shaft, but the dry one looks like it is coming from inside :eek

I made a quicky fitting to into the fuel neck to inject 5 or so PSI of air to maybe I can hear the air leaking. I used a quick release air fitting and fluid dispensing cone from the 99cent store, but I need to wait for my helper, so I can crawl around to hear the air :smile

Martin
 

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#16 ·
Okay some pontification here....

The I could not find this "Valve51" unless it is MOT up in engine area, but the description is safety/over pressure PASSIVE valve, so either it does not exist, or it is up in the tank area because I not find it under the car, and it is not the charcoal relief valve as the charcoal relief is after the canister, so I will go play doctor at the junk yard tomorrow.

The the two lines go into a soft bulk head seal like the thickness of a CV boot. The hose with the wet spot is oil, and not fuel :frown . That dry line goes all the way to the engine area. The other line goes directly to the charcoal canister...

This is where it stands :|

Martin
 

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#17 ·
Looking at the diagrams, it should be first-off from the tank. It's a back-pressure regulator that should maintain 30-50 mbar in the tank

I get the same diagrams for my diesel. I tried looking with a mirror but can't really see - I only have ramps and haven't been under that part of the car yet, I really need to get some good jack stands.
 

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#18 ·
Thank you for the diagram, yet that valve(back pressure regulator) must be on the other side of part 72 which is what I took a picture of.

30 to 50mBar? Meanining MilliBar????? that is 0.43 PSI to 0.72 PSI... Ohhh, I know this pressure is MUCH GREATER on our cars, and much greater when we hear the swooosh..... when we open the tank....:|

Thank you for the info, and that regulator must be somewhere else...

I will go to the junk yard in a day or tooo to find out...

Martin
 
#19 ·
Sounds like you need a smoke machine to inject smoke in the tank then you can see all the leaks:smile
 
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#20 · (Edited)
Sometimes I have rocks in my head that I need to have a real answer...

Got very scientific with this, and conducted all kinds of experiments to "Qualify" what is good and what is not?

1) Those nice diagrams of this valve and stuff in the tank area. They MEAN ZERO(Big Zero). All of that stuff is inside the tank, and that "valve" is inside too. I removed a tank from a 99. One just removes the four 13mm nuts(need a deep socket, or ratcheting wrench) at each bottom corner of a tank. Remove the two hoses from the picture on post 13, and remove the nut to the hose going to the fuel pump. Unplug the connections at the tank, and remove the gas cap :smile. Lift the tank from the driver's side, and roll back from the top, and she will come out... It is nice to practice on someone else's car :devil

2) The air leaking I mentioned on one of my posts is the charcoal canister valve, so this leads me to "Logic of operation" that one needs get....

3) P0455 comes from no "pressure" in the tank which is the sending(pressure) unit with three-wires mounted to right of the two-wire fuel level sending unit on the round part that is on the tank... Automatically (parts changing world we live in) no one qualify's the parts for operation, yet their is nothing wrong changing parts, but these are in the three-digit in price, so I elected test it as it does not have test procedure.

4) The logic of this system:

A) While the car is off. The canister purge valve(Y58/4 on schematic diagram) is normally open(venting the tank-Per the literature-tested too), yet it does not go with what I encountered with my S320 with no battery connected I get the "swoosh" when opening the fuel tank cap... every ten minutes.... The purge valve is what seals the vapor recovery system through the car's computer. Once the key is in position 2 the valve closes-This is written...

B) The tank purge valve(MOT on the valve- Y58/1 on the schematic diagram) is the key to making everything work, but it needs to have a perfect seal from the valve to the tank, so on these cars get the best vacuum, but then can get slow, yet some say you can clean them, and some say to replace. I tried cleaning mine(not that it did not work), and mine stop working. On some other cars one can hear this valve work, but on our cars this valve is quite. One need to wrap you hand around it to feel the pulse. Remember this valve is slowly creating vacuum in the tank. The Pressure for me was about 22” of vacuum from both ends of the valve

C) The pressure sensor in the tank(B4/3 on schematic diagram) is a active sensor.+5v isolated voltage feeds the sensor, and through the pressure in the tank the return voltage drops. From my testing at ambient pressure the output voltage is around +3.00, yet under full engine vacuum(bypassing the MOT valve) in 20 seconds voltage is going to 2.00v enough to get the swoosh when opening the tank cap. This proves their is a seal. After a minute the voltage is like 1.5v to 1.2v, the tank pressure connector is angled at 10 and 4 O’clock. The pressure sensor has three wires. The center is ground. The wire at 10 o’clock is +5.0v bias voltage(it is very precise). The return wire is at 4 o’clock. Notice the I did not mention wire colors. Well… The Mercedes diagrams do not match in colors to what is in the car. This 5v must be rock stable if it is not the problems are much bigger as a modern car is nothing more than pile of instrumentation sensors with precision voltage references-It is the key to the low resolution accuracy. That the voltage reference needs be Dead-On accurate...

The diagrams tie everything to "N3/10" it is a pain to open up the connector on the main computer, so one has to just go to the sensors. I'm glad I did not need to take the left rear tire for the forth-time to get to the charcoal canister.

Observations,

A) When I bypassed MOT valve, and plugged the engine vacuum straight in. After about 5 min of idling the ASR light came on, and idle jumped to 1200 to 1500rpm Scary, but it resets once you turn off the engine.

B) Once the tank is getting full vacuum after just a few minutes the check engine light goes OFF-Yaaayy…. What this says I just need more vacuum

C) After 15 or so seconds the tank gives the swoosh sound, and the tank pressure return voltage is around 2v if I open the tank cap to equalize the pressure with the outside, the tank pressure reading goes to about 3v, and upon installing the tank cap in 15 seconds the tank pressure return voltage is around 2v, yet I open the tank, and I get the swoosh, sooo(A BIG SO) this proves the tank pressure sensor works. The carbon canister valve is shut and working, and the gas cap works….:nerd

D) My theory to “game the system” is to make a voltage divider with two resistors, so the tank thinks it is pressurized. basically the resistors are across the 5v to ground, and one is 3v one resistor, and the other is 2v(remember 2v gave us the swoosh):angel

E) I will install a new MOT valve, and drive around. If it does not work, I will do my voltage divider to fool the system…

F) Lastly, the MOT exit hose to the aluminum line that goes to the tank. Is usually very hard. It is hard on all the cars I have, but on my 2002 E-class Mercedes installed these one-use hose clamps that seal really good, so change that hose, and change the hose clamps like the style used for the coolant hoses,,,

I hope this helps someone as I privately talked to someone, and they got rid of a car because the cost were sky rocketing because of this problem, so this is the reason to qualify not to “parts change”…

Ahhh, one last bit... On my 1996 S320 all the parts are identical(Canister Purge Valve, Tank Purge valve, and tank pressure/fuel level sending unit), yet my S320 did not have the Pressure Sensor connection installed, nor did I see the connector, and wire harness there, so maybe it has been modified by someone else. I will further investigate that too. It was a bit fishy when I did not see the connector on the pressure sensor...

Martin

Edit in these Covid times August 2020. I included two new attachments regarding the voltage range from the StarTecInfo
 

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#21 ·
Excellent write up! This is my preferred way of dealing with problems! Diagnosing is cheap, changing parts is not! :p

That bit with you bypassing the MOT valve and it pressurizing alright makes it sound like the valve is at fault, in my opinion. Let's hope that's all it is and you won't have to go making a voltage divider!
 
#22 ·
Thank you Thank you- I'm just trying to wrap my head around the problem...

I THINK, the MOT is there, so the car does not go into ASR mode with full vacuum, or degrade the tank/hoses/lines under constant twenty-something inches of vacuum...


Martin
 
#27 ·
Did this problem ever get solved?
 
#30 ·
It has been over a month since I have not played with the car :crying

I did build my smoke machine and it worked verywell. I found out one thing I just do not want to do, but it is(I THINK) I have a intake manifold leak. I saw smoke coming out of bottom rear of the intake manifold-behind the throttle body about 4 to 5 inches, so it is not the nipples at the very rear, nor the throttle body(or plumbing near it), but all it can be is a crack in the manifold(rare to see this), or the coupling rubber rings that connect the lower to the upper part :crying MAVA really does not want to do this job.

How I found the leak? I injected smoke from the hose on the engine side entering the "MOT" valve(tank purge valve), and closed off the intake at the MAF with plastic food sealing wrap and a few #64 rubber bands, and I saw the smoke out of the bottom rear of the intake :crying

Because I have been resetting my check engine light. The evap-system has not engaged until the idling and drive cycle(s) have been completed, so the canister purge valve remained open, and I saw smoke coming from there too...Nothing was coming from my tank, gas cap, pressure sending unit, and level sending unit...

So my grand theory is maybe I am not generating enough engine vacuum. I do have this little shake on the engine at idle, but not a leak to cause sputtering or a limp mode as I have read....

Here is a very nice way of doing this intake job on a distributor engine, yet the no distributor engines only have one temperature sensor, but it is a good enough guide... See the link in the link

W140 Vacuum supply line...need help! central locking - PeachParts Mercedes ShopForum

My smoke machine is this...



I used "TIKI Wicks"-Outdoor torch replacement wicks

Outdoor Torch Replacement Wicks - 3PK | Jo-Ann

I used a piece of nichrome wire..(heating element wire) it is not just plane-wire.. Make sure measure the resistance is about 2.5ohms which is 6amp draw or so, and cut the piece there.

The mineral oil is available at target or Walgreens pharmacy-ALL the walmarts are out of the oil. I paid $2.00 for the bottle. You find this mineral oil in the isle in the stomach-upset products...

That is what is cooking with the problem...

Martin
 
#31 ·
If the engine does not create enough vacuum, is there is a way to hook up an external vacuum pump to the purge system, to compensate for the lack of vacuum from the engine & drive around to see if P0455 goes away?
 
#32 ·
Joe,

Too late now for me as I broke a bolt, and I JUST DO NOT WANT TO DRILL IT OUT...

http://www.benzworld.org/forums/gen...ke-intake-bolt-m119-but-how.html#post16410122

I guess need to make an induction heater to remove that bolt. Many You Tubes on how to make them, but here is a commercial one:




Put a tee to the purge valve, and a check valve like the one on the break-booster, and running an external vacuum pump.

Martin
 
#33 ·
Yeah, drilling out is messy. If done right you can helicoil in a new thread the same size, or move up to a larger thread & bolt size. If not you can prey that the over-engineering from the M119 team allows for a bolt missing & quality sealant to seal the manifold perfectly in the area of the missing bolt.

You barely rev your engines above 2500rpm so... :D
 
#34 · (Edited)
I finally resolved it, and I will finish off this thread, so it helps the next pour soul who gets this problem, and I resisted to junking this car, but the thought came across half-dozen times, but the reason I resisted is it just drove too well, and this was the first with the W220 internals.

We are approaching three years, and I have about 75 pictures, so I will post nearly all of them, so I will open 8 blank posts, and come in later to add the photos. That will be the reason for the blank posts...

The problem of the P0455 really started January 2016, and that is where my photos start. January 2016 is when I acquired my German Shepard, and she was seven weeks old then, and now she three-years of age. Time flies when you are having fun....

During this P0455, I tried everything. I tried to simulate the pressure signals from the tank to try to fool the computer that the EVAP pressure was okay to pass emissions ( :devil ), but it did not work ( :crying ) as one can see from the signal wires traveling through the troof (channel)of wires on the drivers side, and me and my potentiometers to skew that voltage... :devil:devil

Realizing none of my tricks worked, and it was time to build that smoke machine in post 30 which lead to the leakage of the center o-rings that separate the lower and upper portion of the intake manifold.
 

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#35 · (Edited)
Taking that intake manifold out. Draining the coolant, and in the lovely process. Got to clean the falling debris...
 

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#36 · (Edited)
Draining the coolant

I broke two bolts( IMG_2061 and IMG_2062). The ones that rust-out due to water being just millimeters away !! The rear one was extracted with vicegrips(IMG_2068)

The broken bolts(It was one-the front drivers side) were part of the hold-up. I tried everything, and it drilled out in like four sizes of drill bits, and the threads were cleaned with the same size tap as the bolt :crying:crying That was a royal pain... Thinking of junking the car... Ohhhh yea....
 

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#37 · (Edited)
The rear bolt extracted with vice grips (IMG_2073)

The broken front bolt after several attempts with vice-grip pliers :crying:crying

The car sat dormant for many months like this :crying:crying
 

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#38 · (Edited)
I the dormant stages. I must have sat in someones W140(I cannot remember ), and boy did it have some very soft leather seats, and so I got some from Craig, and those seats are super soft with Leatherique . Totally in love with the car....

My seats are super soft... :thumbsup:
 

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