Intermittent key issues
Thread Starter
Newbie
Joined: Feb 2026
Posts: 6
Likes: 0
1994 E300 4matic, 2005 E270cdi
Intermittent key issues
Hello, i have a MY2005 E270cdi, this morning my key started having some intermittent issues where it wouldnt work, neither the lock/unlock buttons nor would it work in the cylinder. The red light seems to be working on the key, the fuses in the trunk are all good.
When it stopped working first, i replaced the battery quickly and it worked for a few minutes while i drove to work from the parts shop, when i got out again and tried to lock it, it didnt work. Went inside for a few minutes and when i got back out again it worked all of a sudden, thats when i checked the fuses. Google was no help, it was either the key didnt work in the cylinder or the lock buttons didnt work. Is there any troubleshooting i can do? The key is only about a year old and the old battery only a few months at this point.
When it stopped working first, i replaced the battery quickly and it worked for a few minutes while i drove to work from the parts shop, when i got out again and tried to lock it, it didnt work. Went inside for a few minutes and when i got back out again it worked all of a sudden, thats when i checked the fuses. Google was no help, it was either the key didnt work in the cylinder or the lock buttons didnt work. Is there any troubleshooting i can do? The key is only about a year old and the old battery only a few months at this point.
Member
Joined: Oct 2017
Posts: 87
Likes: 11
From: Charlottesville, Virginia, USA.
2004 W211 E320 Sport
Did you hear a whirring sopund when you put the key in, or silence?
If you have a spare key, try that.
Perform the Phone Camera Test
Switch your smartphone camera on and point it directly at the tip of your Mercedes key.
Press any button on the key.
Look at your phone screen; you should see a bright purple/white flash coming from the key's infrared lens. If you don't see it, the key is not transmitting
Also ensure your main and aux batteries are putting out correct voltage.
If you have a spare key, try that.
Perform the Phone Camera Test
Switch your smartphone camera on and point it directly at the tip of your Mercedes key.
Press any button on the key.
Look at your phone screen; you should see a bright purple/white flash coming from the key's infrared lens. If you don't see it, the key is not transmitting
Also ensure your main and aux batteries are putting out correct voltage.
Thread Starter
Newbie
Joined: Feb 2026
Posts: 6
Likes: 0
1994 E300 4matic, 2005 E270cdi
Did you hear a whirring sopund when you put the key in, or silence?
If you have a spare key, try that.
Perform the Phone Camera Test
Switch your smartphone camera on and point it directly at the tip of your Mercedes key.
Press any button on the key.
Look at your phone screen; you should see a bright purple/white flash coming from the key's infrared lens. If you don't see it, the key is not transmitting
Also ensure your main and aux batteries are putting out correct voltage.
If you have a spare key, try that.
Perform the Phone Camera Test
Switch your smartphone camera on and point it directly at the tip of your Mercedes key.
Press any button on the key.
Look at your phone screen; you should see a bright purple/white flash coming from the key's infrared lens. If you don't see it, the key is not transmitting
Also ensure your main and aux batteries are putting out correct voltage.
