key not recognized - MBWorld.org Forums

Dec 29, 2008 | 07:28 PM

manano

Thread Starter

Junior Member

Joined: Apr 2008

Posts: 58

Likes: 0

S350 2005

key not recognized

out of the blue when i tried to open my car this morning by putting my hand in the door handle she wouldn't unlock. First thing that came to mind was that i have a dead battery..

Turns out that i can unlock my car by pressing the unlock button on the key ONLY NEXT TO THE DRIVER SIDE and she unlocks. Then i tried to start the car by pressing the button on the gear shifter and notice 'Key not recognized' message on the display.. Thought to myself, the key has a weak battery. Then i proceeded to turn the ignition manually and she started without a hitch.

When i got home in the evening, i switched keys.. Same problem.

I replaced both key batteries less than 3 months ago..

Any suggestions as to what could be wrong ? I just want to be prepaired before i go to the dealer so i know what i'm up against.

Thanks in advance and happy new year to all

Manano

Dec 30, 2008 | 05:37 PM

sdunham

Senior Member

Joined: Jan 2007

Posts: 333

Likes: 1

From: Colorado

05 E500 4matic, 08 ML320CDI

Be prepared for the Dealer to tell you nothing is wrong... "Key not recognized" indicates there was/is radio frequency interference blocking the ECU's ability to read the key, that's all... It's usually temporary... I took my E500 in for the same problem and they said they found nothing wrong... I replaced both batteries too and it had no effect whatsoever... They'll blame it on cell phones, radar detectors, location of key in the car ( pocket of coat, pants, etc. ) They also told me "sometimes you just need to put the key in the ignition for awhile" ...

Jan 8, 2009 | 01:30 AM

manano

Thread Starter

Junior Member

Joined: Apr 2008

Posts: 58

Likes: 0

S350 2005

i went to the dealer yesterday. They told me that the ECU needs to be reset, thats all. They'll charge me minimum labor. Need to leave the car with them for a couple of hours.

I might go and leave the car with them tomorrow.

I'll post a follow up...

Jan 8, 2009 | 06:50 AM

Pauly

Junior Member

Joined: Dec 2008

Posts: 26

Likes: 0

From: Suburban Chicago

2003 S55

I have the same problem with mine. The key card will never work in my garage at home. Apparently its attributable to the garage door openers having the ability to constantly modify their frequencies so that nobody can copycat their signals and break into my house. By the same token, it works perfectly fine at my office. I think it's simply a system that is very easily affected by outside interference.

I would however like to know if your problem is completely solved by the dealer resetting the ECU, so please do post a follow up.

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