Tips on making key work in door and trunk?
Thread Starter
Junior Member
Joined: Jun 2012
Posts: 37
Likes: 2
From: Coeur d'Alene, Idaho
1998 C43 AMG
Tips on making key work in door and trunk?
Have a 1998 C43 AMG, battery dead got locked out. The key inside the fob goes all the way in the driver door lock, but won't turn left or right. That key only goes halfway inside the trunk lock, won't turn left or right. Sprayed WD40 in there multiple times, no progress on either lock. Cautious against using anything stronger like PB blaster . Anyone else have this problem and find a solution? I live in Coeur d'Alene, Idaho, lots of salt use on the roads in the winter. Thanks in advance.
Senior Member
Joined: Jun 2019
Posts: 459
Likes: 65
C43 AMG with a tune up
Looks like your cylinder locks has seized if you can't unlock with your blade key?
What you can do is to oil up and wait.
You may also use a tool for a better grip when you try to unlock with blade key.
Worst case scenario, if it doesn't work you might have to buy new cylinder locks?
If you can try and connect a starter cable to your alternator underneath and connect to a power source maybe you can unlock the car
What you can do is to oil up and wait.
You may also use a tool for a better grip when you try to unlock with blade key.
Worst case scenario, if it doesn't work you might have to buy new cylinder locks?
If you can try and connect a starter cable to your alternator underneath and connect to a power source maybe you can unlock the car
MBWorld Fanatic!
Joined: Feb 2010
Posts: 1,506
Likes: 130
From: Bolingbrook Illinois
1999 C43 Amg
Have a 1998 C43 AMG, battery dead got locked out. The key inside the fob goes all the way in the driver door lock, but won't turn left or right. That key only goes halfway inside the trunk lock, won't turn left or right. Sprayed WD40 in there multiple times, no progress on either lock. Cautious against using anything stronger like PB blaster . Anyone else have this problem and find a solution? I live in Coeur d'Alene, Idaho, lots of salt use on the roads in the winter. Thanks in advance.
You can also try attaching the key with a plier after the PB has soaked for a while and heat the key real good and stick it inside the hole and turn real slow taking your time.
As far as the trunk lock man that’s even harder.
Thread Starter
Junior Member
Joined: Jun 2012
Posts: 37
Likes: 2
From: Coeur d'Alene, Idaho
1998 C43 AMG
Thanks very much, that worked on the driver door! Working on the trunk now, key will only go halfway in.
just use the pb blaster nothing is going to happen accept hopefully it will loosen the cylinder. If you get it on the paint just wipe it off.
You can also try attaching the key with a plier after the PB has soaked for a while and heat the key real good and stick it inside the hole and turn real slow taking your time.
As far as the trunk lock man that’s even harder.
You can also try attaching the key with a plier after the PB has soaked for a while and heat the key real good and stick it inside the hole and turn real slow taking your time.
As far as the trunk lock man that’s even harder.
Senior Member
Joined: Jun 2019
Posts: 459
Likes: 65
C43 AMG with a tune up
For 25 years grime and dirt has entered cylinder causing your lock to corrode inside, now your blade key won't turn and unlock.
Use pliers for leverage and gently wiggle with your blade key, it will take time to unlock.
Use more oil from time to time while you wiggle with your key.
Did you manage to unlock doors?
Do you have the rear seats locked or unlocked?
If you can access trunk from passengers door then unscrew both bolts latch holding trunk cylinder lock in place, then it will pop right up.
There are two oval plastic covers hiding bolts
Use pliers for leverage and gently wiggle with your blade key, it will take time to unlock.
Use more oil from time to time while you wiggle with your key.
Did you manage to unlock doors?
Do you have the rear seats locked or unlocked?
If you can access trunk from passengers door then unscrew both bolts latch holding trunk cylinder lock in place, then it will pop right up.
There are two oval plastic covers hiding bolts
Thread Starter
Junior Member
Joined: Jun 2012
Posts: 37
Likes: 2
From: Coeur d'Alene, Idaho
1998 C43 AMG
Thank, when you say use more oil, what kind of oil?
For 25 years grime and dirt has entered cylinder causing your lock to corrode inside, now your blade key won't turn and unlock.
Use pliers for leverage and gently wiggle with your blade key, it will take time to unlock.
Use more oil from time to time while you wiggle with your key.
Did you manage to unlock doors?
Do you have the rear seats locked or unlocked?
If you can access trunk from passengers door then unscrew both bolts latch holding trunk cylinder lock in place, then it will pop right up.
There are two oval plastic covers hiding bolts
Use pliers for leverage and gently wiggle with your blade key, it will take time to unlock.
Use more oil from time to time while you wiggle with your key.
Did you manage to unlock doors?
Do you have the rear seats locked or unlocked?
If you can access trunk from passengers door then unscrew both bolts latch holding trunk cylinder lock in place, then it will pop right up.
There are two oval plastic covers hiding bolts
Senior Member
Joined: Jun 2019
Posts: 459
Likes: 65
C43 AMG with a tune up
You need penetrating oil better than crappy WD40.
Have you tried cleaning the lock with air pressure?
Spray with oil it will soak the internal parts put the nozzle into the lock and compress air into it.
If you don't manage to open trunk you might have to buy a new cylinder lock?
Have you tried cleaning the lock with air pressure?
Spray with oil it will soak the internal parts put the nozzle into the lock and compress air into it.
If you don't manage to open trunk you might have to buy a new cylinder lock?
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