Mcfancy14

When the driver door is open, and then pressing the lock button, the doors won't lock? Has something been disabled because my keys are in my pocket?

Swordfish99

Are you sitting in the car? The car won't let you lock your keys in the car. If I forget my keys in my golf bag and try to lock the car it won't lock it. However, the ME app will lock the car when the keys are in the car.

Mcfancy14

Nope, it's when I'm standing outside.,..I've not had any of my other makes do this. I get it if you're sitting inside. And even if the keys are in the house the lock button doesn't lock..... The only solution is to hunt down the key fog... Ugh

MBguy013

I think I had something similar happen to a non-Mercedes vehicle I used to have. Have you tried pressing the button twice or pressing and holding the button for a few seconds? I don't recall which but I think that's what I had to do with the vehicle.

mikapen

Sometimes when I have another metallic something in the same pocket, it seems to shield my MB key. Now I keep my house keys in a separate pocket.

I know that manufacturers have reduced the power of key fobs in the past year or so, to avoid cloning.

In your more recent post it seemed to imply that your keys were in the house. If that's the case, I'd think it would be a good thing that the key has to be present for somebody to lock the car.

Mcfancy14

Had the same.thought...no luck...

hatata

Make sure when you’re locking the car you’re not pressing the button 3 times in rapid succession because that disables the key fob and when you touch the door it won’t do anything. You can try unlocking the car then touching the door if it doesn’t work then something is wrong. Try changing the battery first.

Mcfancy14

Tx but the issue isn't the fob..its..the lock button on the inside near the door handle....

hatata

gotcha sorry I misunderstood.. very weird indeed.

GregW / Oregon

If the door is physically open you cannot lock with the button; use the button only with the door shut from the inside. I believe that since Mercedes has a "deadbolt" feature, putting the door into locked configuration with it open would not allow it to engage the strike when closing.

YoleanDioz

You have to ask for the help of a locksmith and you will need a new locker.

SubPop

Hi,

Created an account solely to reply to this thread as it's one of the first threads that comes up when you type in "mercedes key fob lock not working" into Google.

I had this issue and it was driving me mad, Car would lock most times but unlocking was so hit and miss. The little red light on the key fob would not flash for unlock but would flash for lock.

For me the issue was so simple that I laughed when I figured it out.

I noticed that when I took the back off to look at the battery that the unlock key worked fine each time (red light flashed each time), did a quick google on Merc A180 battery type and discovered the issue

I was using CR2032 batteries in my key fob as that was what the last owner of my car had out in there, however Mercedes key fobs take the CR 2025 battery type which is thinner. The extra physical size of the battery was enough to push away the unlock switch from the unlock button so no contact was made unless you pushed the button stupidly firmly.

Replaced the battery, not only does the key work perfectly but the back of the fob now fits neatly into the housing so no sellotape is needed to hold it together.

If you don't have a CR2025 battery in your key fob, replace it now!

Hope this helps someone, took me ages to figure this out

mikapen

@SubPop very useful.
Thanks.