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I have a 2010 Mercedes E550 that is currently throwing a P0451 code. It had also been producing a P0455 as well. I've replaced the fuel cap and EVAP purge solenoid valve. The previous owner also replaced the charcoal canister. I believe we're chasing around the same issue, but still haven't come across the root cause. Since all of this surrounds the EVAP system, I believe the next logical step is to follow the current code. That would be the EVAP fuel tank pressure sensor.
Does that make sense as a next course of action?
If so, I'd like to know if anyone has information on where the sensor is located in my vehicle and any replacement instructions. The closest I got was a video on a 2007 S550, but I'm not sure if it'd be the same for my 2010 E550.
I also understand that this could be way uglier, like bad wiring, ECU fault, etc. However, the condition of the vehicle and the place I got it from leads me to believe it was well taken care of. So, that's why I'm starting here. Please let me know if I'm on the wrong track.
Last edited by nathon; Jan 5, 2020 at 09:16 AM.
Reason: Updated formatting
I'm in the same place you are with my E500. I've replaced the gas cap, purge valve, canister shut off switch, rubber hoses and clamps connecting all of them. Tried smoking out possible leaks but haven't found any. Even tried smoke testing the canister but didn't find any along it or where the shut off valve connects to the canister. Now I'm down to the last two most expensive parts: the canister and the ECU. I never got the pressure sensor error but have been wondering if that might be the cause. I'd even be willing to entertain hacking some way to trick the computer into thinking that it passed the pressure test at start up. The part that gives me pause is that after clearing the P0455 it comes back within 3 seconds, no matter where the fuel level is. It was my understanding that it only ran that test when the fuel level between 3/4 and 1/4 tank (or something like that). I've cleared it when it was full and almost empty and it still immediately comes back.
I have an update on the evap saga. I took my car to an import mechanic. They were able to test and verify that the fuel tank evap pressure sensor was bad. Now we've replaced every part in the evap system except the charcoal canister (since that'd already been replaced). After replacing the fuel tank evap pressure sensor, the check engine light went away. I had the mechanic run the car to get the emissions test performed, since it was time to renew registration. That was successful. However, as soon as I got the car home, the check engine light came back on. I spoke with the mechanic, who is incredibly frustrated with my car. He said that they have tested the entire system and it holds both vacuum and pressure across the entire system. Every component is verified to be working properly. Yet, still I get a check engine light.
How does a car with a perfectly working evap system, throw evap error codes? The mechanic mentioned that it might be an ECU problem or need the thresholds at which a code is thrown updated in the ECU, to make it more tolerant. At this point, I'm driving the car and trying to figure out what to do next.
Thanks for the replies. It's at least nice to know I'm not the only one having this issue. I recently purchased another OBD2 scanner so I could get more details.
Currently I am showing the following codes. They have changed a little since first diving into this issue and sending it to the mechanic.
P2422 - EVAP System Vent Valve Stuck Closed
P0451 - EVAP System Pressure Sensor/Switch System Range/Performance
Mode 6 data shows the following bad or out of range values
I saw the post on oil in the ECU pins. I haven't checked the ECU at all yet. I'll have to see how hard that is to get at and check it. I'll follow up as I know more. Hopefully we'll all find the root cause. I love the car, so it'd be nice to be ble to run it through DEQ.
Thanks Senecat! I had assumed he meant with the purge vents and valves commanded closed, but thanks for the info! I own the WIS/EPC software. I bought it shortly after I purchased the car and realized that there weren't many service manuals available for Mercedes. However, I'm having a difficult time tracking down the correct wiring diagram (or at least verifying it's the correct one). The wiring diagram I found is document number "pe07.61-p-2101-97dab". It shows that the purge control valve and charcoal filter shut off are connected to the ME-SFI control unit. Can someone verify that I have the correct wiring diagram and if so, tell me where the ME-SFI control unit is located? I've included a snippet of the part of the diagram that shows the purge control valve (Y58/1) and charcoal canister (Y58/4). The N3/10 label designates the ME-SFI control unit.
Vehicle Info
2010 Mercedes E550 Luxury 5.5L V8 Bi-turbo non-ECO version with pretty much all the "bells & whistles" (e.g. panorama roof, air suspension, massage seat, A/C seats, etc.).
Thanks for the replies. It's at least nice to know I'm not the only one having this issue. I recently purchased another OBD2 scanner so I could get more details.
Currently I am showing the following codes. They have changed a little since first diving into this issue and sending it to the mechanic.
P2422 - EVAP System Vent Valve Stuck Closed
P0451 - EVAP System Pressure Sensor/Switch System Range/Performance
Mode 6 data shows the following bad or out of range values
I saw the post on oil in the ECU pins. I haven't checked the ECU at all yet. I'll have to see how hard that is to get at and check it. I'll follow up as I know more. Hopefully we'll all find the root cause. I love the car, so it'd be nice to be ble to run it through DEQ.
Is your EVAP reporting too much vacuum or not enough ?? That knowledge is essential to focuss on different parts.
Low Vac ... Have you concidered the two sealed tank access covers on top (pump/filter) that like to crack, leak and smell ??
EVAP vacuum sensor should read near seal-level pressure with an open gas cap at rest. This will help you partially rule out wiring, ECU issues.
EVAP Monitor:
Computer closely monitors tank EVAP to confirm it does not leak any vapors stored in charcoal canister. It does that by shutting off tank vents, pulling a vacuum at once from intake plenum and measuring it over a period.
Now try to understand where your EVAP test fails. Look at live data after engine start.
With all the new parts replaced for no reason, this job is nearly complete.
Last edited by CaliBenzDriver; Sep 6, 2021 at 09:32 PM.
Thank you for the insights Cali. The information captured in this thread is the totality of what I know about the issue, as well as the readings I have. Since so many people have this issue, I'm trying to work this issue together, as an MB community. My hope is that if we can get to the bottom of the issue, it'll help others with this issue as well.
I'm reasonably knowledgeable in automotive mechanics as well as general electronics. I've rebuilt several top ends of engines, can perform whatever maintenance or repair I need on my vehicles. I'm also a software engineer and develop my own electronic PCBs as a hobbyist. However, I'm not well versed in what the OBDII codes can be affected by (other than the obvious) as well as normal and atypical ranges for each OBDII reading or what unit they're in. If the issue is exactly what the code says (e.g. purge valve), I'm fine. However, I have replaced literally every component in the evap system on my vehicle and still have the issue. Thus, I'm trying to work with those more knowledgeable than I to come to a solution.
In this situation, I don't know what too low or too high would be for the vacuum system. I also don't know what pressure reading would represent sea level. I can see the values are represented in hexadecimal, so I can do the conversion. However, is that reading PSI, some arbitrary range that converts to PSI, something else? I'm also not sure what the procedure is when the vehicle starts, warms up and runs. Is it supposed to keep the valve closed until the engine warms up. Then if it detects too high of vapor pressure in the tank, it opens the purge valve and directs the vapors to the intake to be burnt?
Thank you for the insights Cali. The information captured in this thread is the totality of what I know about the issue, as well as the readings I have. Since so many people have this issue, I'm trying to work this issue together, as an MB community. My hope is that if we can get to the bottom of the issue, it'll help others with this issue as well.
I'm reasonably knowledgeable in automotive mechanics as well as general electronics. I've rebuilt several top ends of engines, can perform whatever maintenance or repair I need on my vehicles. I'm also a software engineer and develop my own electronic PCBs as a hobbyist. However, I'm not well versed in what the OBDII codes can be affected by (other than the obvious) as well as normal and atypical ranges for each OBDII reading or what unit they're in. If the issue is exactly what the code says (e.g. purge valve), I'm fine. However, I have replaced literally every component in the evap system on my vehicle and still have the issue. Thus, I'm trying to work with those more knowledgeable than I to come to a solution.
In this situation, I don't know what too low or too high would be for the vacuum system. I also don't know what pressure reading would represent sea level. I can see the values are represented in hexadecimal, so I can do the conversion. However, is that reading PSI, some arbitrary range that converts to PSI, something else? I'm also not sure what the procedure is when the vehicle starts, warms up and runs. Is it supposed to keep the valve closed until the engine warms up. Then if it detects too high of vapor pressure in the tank, it opens the purge valve and directs the vapors to the intake to be burnt?
Thank you all for your help!
I am 100% not familiar with Benz particular EVAP system and have never delt with any of its surprises.
Your best bet would be to figure what is the usual EVAP part that cures these cars. In absence of that you may need to get famiar enough with the system to test it where all other mechanics who worked on your car have failed you so far...
P2422 - EVAP System Vent Valve Stuck Closed>> Sounds like ECU is complaining about a high vacuum it's not able to equalize by opening the EVAP VENT.
ECU reads the tank vacum with the stupid hexadecimal sensor - You can translate these values in standard decimal values. As you noted, who knows what unit they are in...
Concider relative vacuum values: 1- open gas cap, engine off : this is ambient air pressure ("sea level" base reference if your near the coast)
2- tank sealed, engine running: you want to note the difference in value. This will denote a vaccuum pulled from plenum.
3- open cap, engine off: this should be back to #1 reference value. That's when the ECU sets code because your tank stays under vacuum as reported.
You may just have a simple blockage of air vent inlet with dirt....there is an inlet filter to canister.
PURGE is the ECU ticking valve drawing a metered vacuum from plenum.
VENT is the valve allowing air in the canister while engine is drawing vaccum on it. That is where your problem seems to be. That is not letting enough air.
A WIS document would provide you with more system details and perhaps provide a complete guided test.
✌️
Last edited by CaliBenzDriver; Sep 19, 2021 at 11:13 AM.
Thanks again Cali! That was super helpful and just the right amount of detail. I'll try to spend some time on this in the near future. Unfortunately the industry I work in (healthcare) is a bit nuts at the moment, so I haven't had much time to dig back into this myself (other than to grab the OBDII readings). When I get more details, I'll reply again.
@nathon have you checked the ECU pins for oil? Also check the cam position sensor connectors and cam solenoid connectors for oil. It’s 20 minutes worth of effort and will rule out a potential cause. If you have oil in the harness causing intermittent open circuits, you will replace every component in the car until the oil in harness is corrected.
I had a CEL related to the evap system and once after filling up my car wouldn't start. Per advice from one of the board members who is a Mercedes tech I eventually made it go away by cleaning the purge valve in the engine compartment with WD40.
Thanks to all those that have been following and helping with this saga. My son and I took off and tore down the air filter housing to clean out some seeds that an enterprising animal (squirrel?) decided to store. While doing so I went ahead and unfastened and checked both connectors to the ECU. There was no corrosion (green junk) and no oil at all inside the connector or pins. They looked absolutely new.
I suggest getting a high lumen flashlight and start tracing the wiring in the area where the wire eating vermin might have been. You may have a short or open circuit somewhere. They might have been rats or mice and they can be very destructive.
I figured I'd better post the final summary to this saga. After taking it to the dealership, taking it to an independent import shop and replacing nearly every evap system part... I took one last stab at taking it to the dealership. I needed an oil change anyway, so I figured why not. This time they figured out that it was the evap purge valve solenoid. That was the first part I replaced, but it would seem that I got a bad new part, which lead to the rest of this mess.
Thankfully the check engine light is now out and it got a completely clean bill of health. It wasn't a complete waste. I did get some coolant and oil leaks fixed up at the independent shop as well as water pump and some other miscellaneous items. The dealership said they haven't seem a 2010 model in this good of shape and low mileage (~60K). It's finally fixed! Thanks to everyone who helped me through this!
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2010 Mercedes E550 EVAP Pressure Sensor
Update
Thanks All!
