zcct04

What the subject line says - my keyless-go spare will lock & unlock the doors if I push the tabs on it, and it'll let me use the door handle to lock & unlock if the fob is in my pocket, but when I try to start the car with it I get a "key not detected" message on the dash. This is the first time I've tried using this key. The car is a 2012 that I've had for about six months. I've got nothing else in my pocket to interfere. Any advice?

Dr Matt

Key needs programmed. When I got my CL it only came with one key. Ordered a second from the dealership and when it arrived it worked like yours, everything fine except keyless go. Had to take it in to the stealer ship and have it "coded".

JimmyR

You could try starting the car using the key in the ignition, after first removing the starter button. This might allow the car to recognise the key and save you a trip to the dealer. I have had this happen once with mine (I just can't remember if I had the "Key Not Detected" message or not), and when I used it in the ignition switch it worked fine and no problems since (though no doubt I will as soon as I finish typing this)...

zcct04

Thanks JimmyR - this didn't solve the problem but it helped. I'd never removed the start/stop button and actually started the car with the key in the ignitin before, and I now know that I can use the spare if I get in a bind. Unfortunately, I'm still getting the "Key Not Detected" message when I try to start it without putting the key in the ignition.

Suepermann

Replace keyless-go battery?

zibby43

+1 (if all else fails, this is a fairly cheap solution)

However, OP, you might want to try this first . . .

My key does this too if I've spent too much time around the car with my key in my pocket. The keyless entry will work just fine but the key won't be detected at start-up. If I simply move the key toward the steering column (without taking out the Start/Stop button), the car will pick it up and subsequently start just fine.

zcct04

I drug my feet on the battery change - with the car in the garage, I could lock/unlock with the key fob from most of the rooms in the house, so the battery seemed like it wasn't a problem. I replaced it anyway, and things now work perfectly.

This forum is awesome - thanks guys!

Suepermann

I don't post much as you can see, but I thought I'd throw my 2 cents in. I'm always replacing the keyless-go after I receive the 'key not detected message". If I wait to replace the battery, I'll usually get the "replace battery message" some time later.

Next i'm gonna try the 2032 battery vs the 2025. Not sure if it will fit….but what the heck!!! Maybe I can get more life and stability out of the keyless-go.

Anyways, glad to help.

bluejae

i've had this happen even after a new battery... it's possible it could be a bigger issue...

one time the car wouldn't even unlock for me when i was next to the car... but i could use the button on the key to unlock the car... when it wasn't unlocking, you would see a message on the dash saying this PRE-SAFE CONDITIONS LIMITED. SEE OPERATOR'S MANUAL...

i ended up taking it to the dealer and they traced it to a short in the wiring on of the receiver antennas in the driver's door.

Spearsba

Sme with keyless-go on my C63 and ML. New battery and no more issues.

bigg dogg

I too had been experiencing the issue with my C350. Dealer says they couldn't reproduce the alarm but said that one of the door handle was an issue. I changed the handle last year. Problems still there. Yesterday my car wont start. It's going to cost me over $1200 to change the EIS. I wonder if the problem was the EIS all along. I read lot of thread relating to the EIS failing. I know this is on old thread you posted.

HBC350

Mine did the same thing. Replaced the keyfob battery and all was well again.

zcct04

Tried this yesterday on my 2012 keyfobs. 2032 battery does NOT fit.

roadtalontsi

just throwing this some more info out there for future reference. If you have an rf-id blocker in your wallet or purse it will cause issues with blocking the signal for keyless go. Additionally depending on the conditions your key sits in .... In some cases static electricity can charge the key up and disable the chips temporarily. All it takes is that you press any button and it will go back to normal and work again.

If this repeatedly occurs, Id recommend picking up one of the leather or rubber key covers to help protect from electro-static discharge.

bigg dogg

Chip removed and code for new assembly installed to recognize key. 1200 bucks.

bigg dogg

Chip removed and code for new assembly installed to recognize key. 1200 bucks.