How a car key works

Keys are unchanged for centuries, as are the methods for “picking” a lock. Even though cars have been around for much less than this, your car key is still going in a lock, just like the yale locks and euro cylinder locks used on your house door.


In its simplest form, your car lock is just a simple cylinder that you slide your car key into and then turn. The cylinder pulls a cable that pulls the lock mechanism out of the mortice. That is why old locks could be forced by jamming a screwdriver in them and turning.

The cylinder, or more accurately the core of the lock is shaped so the key often has grooves cut along its length. This means the key has to be the right width, length and profile to fit all the way in. However this means that any key for that kind of lock would work!! For this reason, all keys, including car keys, have either edge cuts, or increasingly, a “laser” cut along the face. This makes keys individual to the lock.

So what do these edge cuts or laser grooves do?

The core of your car lock has spring loaded pins or wafers that drop through small holes in the core and act like a ratchet to lock the core in position. Each wafer or pin is moved to an exact position to allow the core to turn when the correct key is inserted. The wrong key will move them too far, or not far enough and the core will remain locked

Following me so far? Good, easy isn’t it?

So when we go to a locked car, our job is to pick the lock, which means we use specialist tools to maintain a little turning pressure on the lock, while moving those pins or wafers into the exact position the key would, until, hey presto, the lock turns and the car opens. How do we know the correct position?

All by feel. Remember I said that the pins and wafers are spring loaded? We use this to“feel” for the tension on the spring to know that it’s in the right position and use the slight turning force on the lock to hold that pin or wafer in position.

Locks are well engineered and have a clutch on them. Too much turning pressure on the lock core and the clutch allows the core to turn independently of the lock mechanism, so the car remains locked.

Start again. It takes a lot of practice (and failures) to learn the “feel” of the springs and the exact torque to place on a lock you are picking.

So if you have locked your keys in the car, it is now open and you can be on your way. But what if you have lost your car keys?

At this point, our trusty lockpicks become depth and space gauges. That means we can measure, very precisely, exactly where each pin is, and how far we have had to move it to unlock the car. With this information, we can select the correct width, length and profile car key blade and code the cut, or “bitting” information into a small CNC key cutting machine that will replicate the lost car key exactly.

Phew. Day saved. Despite losing your car key, we have now cut you a new one. This is where car keys have really changed dramatically over the years. It will not start your car until we get to grips with the advanced electronics and computer programming that lives in your car key, and taught the car to talk to the key, and accept what it says.

But that’s another story for another post.


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