What Causes a Key to Insert but Fail to Unlock?
2 Answers
Excessive key wear. Below are the detailed explanations: Key grooves: The key has grooves that push open the spring plates inside the keyhole. When all grooves are properly aligned, they form a straight cut, allowing the key core to rotate smoothly and unlock the door. Excessive wear: However, if the key is excessively worn, the spring plates may not be pushed open enough to form a straight cut, causing the plates to jam the lock cylinder and prevent rotation. This is typically the result of prolonged key usage. In such cases, only a spare key can be used to open the door. Regularly injecting lubricating powders like graphite into the keyhole can reduce friction and minimize key wear.
Yesterday I encountered the same situation - inserted the key but couldn't turn it, sweating from anxiety. There are typically three common causes: issues with the key itself, lock cylinder failure, or external force interference. Since my spare key worked, it indicated the original key's teeth were worn down. If the spare doesn't work either, it's likely a lock cylinder issue - stuck pins, broken springs, or rust from previous car wash water ingress. Another possibility is door deformation squeezing the lock cylinder, requiring inspection of door frame gaps. For rusted locks, spray some rust remover and wait ten minutes before retrying - never force turn to avoid breaking the key. If pins or springs are damaged, the only solution is disassembling the lock to replace components.
