View Full Version : Fuelling door won't open...

12-02-2012, 08:01 PM
Hi guys,
Went to fill up today and the gas cap door is stuck in locked position. I tried locking/unlocking & turning ignition/car on and off a couple of times to no avail. Has anyone run into this before? (1993 500E)
thanks in advance.


12-02-2012, 08:26 PM
There is an emergency release for the door on the inside of the fuel door vacuum element on the inside of the trunk, that will allow you to release the fuel door. It is likely that the vacuum element has failed, though it could be a vacuum supply issue as well. Best way to test it is with a MityVac or other handheld vacuum pump.


12-02-2012, 09:11 PM
Thanks Gerry - that's great info. I will give it a go. Where's the Austin Powers pump when one needs it?


12-02-2012, 10:44 PM
It should be a little red knob that you pull to move the vacuum element so that you can open the fuel flap.

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12-03-2012, 12:08 AM
N.B.: Be careful that you don't pull too hard. The red knob will break off.

12-03-2012, 09:06 PM
When I took the car to the dealer today for assessment, it was working again! It must have been just stuck. At least now I know where the emerg release knob is if it happens again.
Thanks again guys - great resource!

12-03-2012, 10:15 PM
There's a good chance it may get "sticky" again. Sometimes the metal pin (see the lower part of the photo below) that moves up and down and actually "locks" the fuel door, rubs against the hole that it fits into and may get a little sticky. Either that or the rubber diaphragm inside the actuator is starting to fail. In any case, tt's a fairly inexpensive bit to replace, if necessary.

Part number: 129 800 20 75

AutohausAZ has the gen-u-whine MB part for around $58.00 + free shipping.

Parts.com has it for $43.80 + probably around $8-10 shipping & handling (combine with other items to lessen shipping costs).



12-04-2012, 09:14 PM
Thanks Gerry - you the man! You are probably right - I am being overly optimistic. If it happens again, I'll replace it.

Cheers. Mark