Hello everyone,


I recently purchased a C450 AMG in July and was taking it to my near by car wash (softbrush) wash. As I got out of my car to start wiping it down I noticed that my fuel cap door had broken off. I couldn't even believe it. In all the previous cars I have owned (2 Mercedes C classes before it and a 15 ML) I've never had this issue. Anytime you drive and have auto lock on the doors and fuel cap are to lock.


I called my dealer and apparently on these new models its a safety feature as there is a safety Decoder reader on the fuel door when you open it. The problem is why would they design it this way where the fuel cap door can easily be opened when driving. Now I have to resort to a touch less car wash and or hand wash it (which is not a problem until winter comes)


Has anyone had this experience or know if this is just my issue or a way to actually have it lock when driving? I know when I park the car and lock it the fuel door then locks.

 

never had this issue.

and i only go to auto car washes (the $8 kind). only downside is car gets full of swirls, but it's a lease for me, so i'm not going to detail it myself or pay for someone to detail or hand wash it.

 

Unless I drove a $1000 ****ter I'd always wash the car myself. I like to make some effort and am lucky enough to have a driveway.

that said, fuel door alignment is poor on this car.

 

The fuel door should lock whenever the doors are locked. If you have the auto door lock feature engaged, the fuel door should be locked when you're driving.

 

That is my point, the fuel door does not lock on the new C class models. It stays open which I believe is a terrible design. My dealer told me that due to the safety decoder scanner bar located on the inside of the fuel cap door it stays unlocked due to an accident the rescuers can open that door to scan it to see where the air bags are in case they need to cut into the frame of body and not accidently set off an air bag.


Try it on yours, it won't stay locked. Only time the fuel door seems to say locked is if you park car get out and lock it.

 

First, make sure Automatic Locking is on. I don't know what the default setting is, but you can check it at Vehicle/Vehicle Settings/Automatic Locking. Even when Automatic Locking is on, if you go to the pump first and then don't exceed 15 mph between the pump and the car wash, the doors will not have autolocked. That is exactly what happens with me. So from now on, I guess I will have to drive down the road and back.

I don't know if my fuel filler door autolocks or not. I drive a 2015, and there is no safety decoder scanner bar inside the fuel door. But then my fuel door was replaced when the misalignment was repaired. I am sure the replacement door is from a different model, because the recommended tire pressures are quite different.

 

Why depend on auto-lock? Why not just manually lock the doors before proceeding into the car wash?

The story about the door needing to stay unlocked for rescuers sounds fishy - the door is plastic and could easily be pried open in an emergency.

 

Manually locking the doors doesn't do anything. The fuel door still can be opened. So again, the only time the fuel door actually stays locked is when you are out of the vehicle and you lock it and walk away. Otherwise the door remains open which is just a terrible design.


All my previous models the fuel door locks after you drive a certain speed. My wife has a 15 ML350 and you can drive around block, get out of the car and if you tried to open the fuel door you couldn't until you hit unlock botton.

 

I tested my 2015. With me in the driver's seat, the doors locked, and the engine running (as it is at a car wash), my wife on the outside was unable to open the fuel door. So the unlocked fuel door is a 2016 thing.

"So from now on, I guess I will have to drive down the road and back." Lost my head - of course, I can just lock it manually.