Bad central locking range

[Paulwalsh]

I own a w204 2009 c280
It as really bad central locking range. ive changed the battery in the fob, it made no difference. I can be standing right next to the car and it still won’t work

 

[BillyBoy]

Do you have two keys? If so, do they both behave the same?

The key can work in two modes, radio and infrared. The dark lens on the end of the key is an IR transmitter, this should work if you point it at the recover on the driver's door. You can test the IR element by pointing it at a digital camera and pressing the unlock button, you will see it flash on the camera as the camera sensor also picks up IR. Other possible faults are defective key ( you can get a replacement from a good locksmith ) or defective receiver in the car, however I'm not sure where the remote locking aerial / receiver are on a W204.

 

[Paulwalsh]

Yes both keys do the same

 

[mioba]

Do both keys have poor range With new batteries installed.

If so it’s clearly on the car side. I wonder if there is an antenna on the module that can be replaced.

Hope sometime with more knowledge of the car alarms comes along soon.

 

[BillyBoy]

If both keys have the same issue, that points to the car receiving the signal. Could be the antenna it the amplifier or wiring in between. This may help, though I think it's from a W203, but underlying principle will be the same:

https://mbworld.org/forums/c-class-w203/369639-intermittent-key-remote-tale-intrigue-mystery.html

 

[Paulwalsh]

Yes both keys have had the battery’s replaced. And they both have bad range