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2006 Cls500
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Discussion Starter #1
I have had this happen before :
warning light comes on and says gas cap loose ,,ok I fix it and goes away and then sometimes the check engines light follows ,,and again it goes out ,,HHHmmm!! this time its been 3 days and the light id not going out ?????
and ideas on what I need to do???
thank you
Rick
2000 S430
88k on her
 

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S-430
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I have a S430 and my gas cap is stuck and I can not remove it from my car. Is there anyway that I can pry the cap off, I'm 250 miles from home and I don't want to go to the dealer and pay a extra 3 grand.
 

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The Air Mass sensor is a likely culprit.
One advice: look out for engine stalling when idling at stop lights. If stalled, you might not be able to restart the engine.
 

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2013 S550
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penny649 said:
I have a S430 and my gas cap is stuck and I can not remove it from my car. Is there anyway that I can pry the cap off, I'm 250 miles from home and I don't want to go to the dealer and pay a extra 3 grand.
It's likely a lot less than 3 grand - which your towing fees and screwing up your engine by running out of gas could run.
 

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2003 S500 4MATIC
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^^What did he reset and how?

penny649 said:
I have a S430 and my gas cap is stuck and I can not remove it from my car. Is there anyway that I can pry the cap off, I'm 250 miles from home and I don't want to go to the dealer and pay a extra 3 grand.
Any mechanic should be able to get it off. It's probably just a little tight.
 

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2003 S500 4MATIC
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I took my car to the dealer and after several hours of diagnosis time they figured out was a faulty charcoal cannister switch (or maybe valve?).
 

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Most often, you forgot to tighten the gas cap at your last refill. It takes three or more engine starts before the Check Engine light comes on. If you tighten the gas cap, the light may go out after three or more engine starts. If not, you will have to go to a service station or buy your own OBD II (On Board Diagnostic version II) code reader. They cost $50 - $100, or more. A loose gas cap is code 170, despite what the code interpreter says about a fuel system bank fault. Use the OBD RESET button to turn off the Check Engine light.

If the gas cap is stuck, get a large open end wrench and put it on the gas cap knob to give yourself some leverage and twist the gas cap open. It will come off as usual with the extra leverage. The gas cap is OK. The problem is that the latches on the rim of the filler tube are bent. Look inside the rim and you will see two little tabs or ears at the ends of each of the two ramps that start at each of the two slots in the rim. They are supposed to catch on the white tabs on the inside of the gas cap. They will be bent back toward the walls of the filler tube, so they don't catch the gas cap. Pry the tabs with a screwdriver and bend them out straight and parallel to the walls of the filler tube so they point straight down towards the gas tank. The entire procedure should take less than 5 minutes.

The dealer will probably tell you that your tripronged bifurcater needs to be replaced and charge you $1000 to do this. If he doesn't, you've found an honest dealer. Please post his name on this website so we can all go to him for service.
 

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Most often, you forgot to tighten the gas cap at your last refill. It takes three or more engine starts before the Check Engine light comes on. If you tighten the gas cap, the light may go out after three or more engine starts. If not, you will have to go to a service station or buy your own OBD II (On Board Diagnostic version II) code reader. They cost $50 - $100, or more. A loose gas cap is code 170, despite what the code interpreter says about a fuel system bank fault. Use the OBD RESET button to turn off the Check Engine light.

If the gas cap is stuck, get a large open end wrench and put it on the gas cap knob to give yourself some leverage and twist the gas cap open. It will come off as usual with the extra leverage. The gas cap is OK. The problem is that the latches on the rim of the filler tube are bent. Look inside the rim and you will see two little tabs or ears at the ends of each of the two ramps that start at each of the two slots in the rim. They are supposed to catch on the white tabs on the inside of the gas cap. They will be bent back toward the walls of the filler tube, so they don't catch the gas cap. Pry the tabs with a screwdriver and bend them out straight and parallel to the walls of the filler tube so they point straight down towards the gas tank. The entire procedure should take less than 5 minutes.

The dealer will probably tell you that your tripronged bifurcater needs to be replaced and charge you $1000 to do this. If he doesn't, you've found an honest dealer. Please post his name on this website so we can all go to him for service.


did you not see that this was a 1.5 year old thread?
 

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What's your point?

I thought these forums are not for a single use? A year and a half later, someone else may have the same problem, and be interested in this thread, as happened to you and me.
 

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Hmmm it happend when i got my check engine light for the first time and it scared the sheet out of me but turned out to be what...gas cap. I closed it tightly and every thing went back to normal. Its fine since then.
 

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did you not see that this was a 1.5 year old thread?
No doubt he missed that, but the answer was worthwhile - especially the part about the tripronged bifurcator. :D
 

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Good news and solutions are never too late.

I thought these forums are not for a single use? A year and a half later, someone else may have the same problem, and be interested in this thread, as happened to you and me.
Well stated slkuser!

One of the most frustrating parts of doing a search on some forums is coming upon threads where someone describes a problem and never gets a response or they never share/report a solution.

Many times no answer is found or given as to what can solve a problem. Then the original poster states that they will go to the dealer or an independant garage to find the answer and report back to the forum, but then they never return and we forum users are left in limbo.

So, thank you slkuser and others like you for your excellent contributions in helping other MB owners solve problems with their cars no matter how 'old' a problem may have been or how long ago it was mentioned!
 

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I have to agree that his post was very helpful, since *my* check engine light came on last night... which freaks me out. And I got gas a couple of hours before, so now I am crossing my fingers that it was the gas cap.

Thanks to all the contributors, this forum is a great source of information.
 

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SLK user:

Your reply was very helpful and you are right. After the original thread, here I am looking for the reason to why my gas cap on my 99 e320 keeps getting stuck. I have had to force it off and then it won't go back on until I force the white plastic ring counter clockwise.

Any chance you can take pictures of your fix for the filler tube and post them here?
 

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I still remember how i felt the first time i saw the check engine light on while driving back from work.....
 

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SLKUser, thanks for your solution!

I have a 99 E430 and having the exact some problem with removing the gas cap. I just stopped by a MB Dealer to get a new gas cap, and I still have the same problem with the new cap. The service manager suggested me to "go home and remove the white plastic under the cap, which he is not authorized to do that, and that should solve my problem." Or I can replace the entire gas tank, which will be costly.

So I came home and searched online, which I found this post. I will go home and try what you suggested tonight and report back later. Thanks!

Your reply was very helpful and you are right. After the original thread, here I am looking for the reason to why my gas cap on my 99 e320 keeps getting stuck. I have had to force it off and then it won't go back on until I force the white plastic ring counter clockwise.

Any chance you can take pictures of your fix for the filler tube and post them here?
 

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As promised, I am reporting back my findings.

As SLKUser pointed out, there are two tabs on both sides of the rim inside the filler tube. (see pictures below).

I was having trouble to straighten the tabs inside with a screwdriver that SLKUser has suggested. Or at least I don't have any tools that would fit to bend it back.

So, my another workaround is:
1. Turn the white plastic under the cap to close (lock) position, so the metal part is NOT aligned with the thicker white plastic part.
2. Round off or cut the thicker white plastic area so now the white plastic is completely round without any part sticks out, that way the white plastic can turn smoothly in the filler tube without getting caught by the metal tabs. Now, the whole purpose for the white plastic is to hold the metal at the height of the lock position. It is important NOT to remove the white plastic. If you do, the spring inside will push the metal to the top of the gas cap, then you won't be able to close the gas cap, or it will be too tight.

I know it sounds confusing, but it will be pretty straight forward if you look at my attached photos.
 

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gas cap

I have a 2006 S-500 and after refilling I did not put the cap on tight enough. After about 125 miles my "gas cap" light came on I rechecked the cap and tightened. After a few starts the light went off.
 
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