c240driver1986

So does your key fob not work ?
C240 2002 -Key Fob
Here is what I did to solve my key fob it took me 3 days to trouble shoot
Just to let you know if you have to buy a new one my local dealer quoted 400$

My issue: Fob would intermittently lock or would be unable to lock randomly
red IR light would blink. was still able to turn car on.


Step 1

Check/Change your battery probably number one issue, it cant hurt.
I placed a small piece of paper inbetween the batttery and battery cover to insure a tight connection, latter on i foundthis to be usefull.
here's a video

Step 2

Still the unable to lock doors with red IR light still blinking ?
dismantle fob and clean the inside of key with air can to blow out dust or grim that may interfere with connection, this solved my problem, reglued it
and vola fob fixed
heres a video

mckenny

Step 2 video is disabled?

AIA

I drive a C240 as well and I have experience same issues with intermittent key functioning. At time the key is not the issue, rather the receiver radio on the car. Changing fuse No. 8 could solve this. Worked for me!