# Door Locks

**URL:** <https://community.cartalk.com/t/door-locks/47042>\
**Category:** Maintenance/Repairs\
**Tags:** c-class, keys, doors, mercedes-benz, locks\
**Created:** [April 6, 2010, 2:41pm UTC](https://community.cartalk.com/t/door-locks/47042 "2010-04-06T14:41:59Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Johanna\_Loc](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/johanna_loc/32/1792_2.png) [@Johanna\_Loc](https://community.cartalk.com/u/Johanna_Loc)\
**Post date:** [April 6, 2010, 2:41pm UTC](https://community.cartalk.com/t/door-locks/47042/1 "2010-04-06T14:41:59Z")

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Two questions:  
  
 Can the key lock button wear out? I have replaced the batteries but sometimes I have to try several times to get the doors to unlock with the button. The Mercedes dealer said I may have to replace the entire it. By the way, pointing the key toward the roof of you mouth does work. I heard that on car talk.  
  
  
  
 Also, does it damage the automatic door locks if you lock or unlock them manually?

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**Author:** ![missileman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/missileman/32/1366_2.png) [@missileman](https://community.cartalk.com/u/missileman)\
**Post date:** [April 6, 2010, 2:58pm UTC](https://community.cartalk.com/t/door-locks/47042/2 "2010-04-06T14:58:01Z")

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Yes…the key fob can wear out and they do quite frequently. No…locking the door manually will not hurt automatic door locks. You would not be able too if it did.

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**Author:** ![Johanna\_Loc](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/johanna_loc/32/1792_2.png) [@Johanna\_Loc](https://community.cartalk.com/u/Johanna_Loc)\
**Post date:** [April 6, 2010, 4:09pm UTC](https://community.cartalk.com/t/door-locks/47042/3 "2010-04-06T16:09:49Z")

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Thank you for your response.

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**Author:** ![lion9car](https://avatars.discourse-cdn.com/v4/letter/l/59ef9b/32.png) [@lion9car](https://community.cartalk.com/u/lion9car)\
**Post date:** [April 6, 2010, 4:43pm UTC](https://community.cartalk.com/t/door-locks/47042/4 "2010-04-06T16:43:18Z")

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If you haven’t used the key much until now, the mechanism may be a little hard to turn. If that happens, make sure you use a lock lubricant (like powdered or liquid graphite) and not WD-40, which can gum up the lock over time.