Why a key stops partway in
A key slides into a narrow slot called the keyway. The slot is shaped by grooves, called wards, that match the grooves on the blade of the key. Once the key is fully inserted, its cuts line up with a set of pins or wafers inside the cylinder. If anything changes the shape of the key, the shape of the keyway, or the space inside the cylinder, the key will stop short.
Four broad categories explain nearly every case. Something is in the way, such as dirt, lint, or a broken piece of another key. The key itself is not right, because it is bent, worn, or is a different key from the one meant for this lock. The cylinder is damaged, either by wear, forced entry, or a previous repair. Or the lock is not what you think it is, and the key belongs to a different lock.
The point of sorting these is to choose the correct response. Debris calls for gentle cleaning. A bent key calls for a replacement. A damaged cylinder calls for a professional. Wrong key calls for a moment of embarrassment and a search through your key ring. Each one has a different cost of getting it wrong, and the worst mistake is forcing the key.
Start with the simplest check: is it the right key?
People often carry a ring full of keys that look alike. Before anything else, look at the key and the lock. Most locks have a brand name stamped on the face of the cylinder or on the key head, and the brand on the key should match the brand on the lock. Check the shape of the blade profile, which is the cross section you see when looking at the key end on. If the profile does not match the opening of the keyway, it will not enter.
Check for a recent change. Did you move into a new place and receive a new set of keys? Did someone rekey the lock recently without giving you the new key? Have you just had a copy made at a kiosk? A copy that was cut on the wrong blank is a common cause of a key that will not go in. The blank may be the wrong brand, the wrong keyway, or a similar looking profile that is a few thousandths of an inch off.
If you have an original key and a copy, try the original. If the original enters smoothly and the copy sticks, you have your answer. A new copy cut from the original on the right blank should solve it. For car keys, the same logic applies, and our guide on types of car keys helps you identify what you have.
Debris in the keyway
Locks collect more than you would expect. Pocket lint, grit, dust, tiny bits of metal from key wear, spider webs, and the remains of old lubricant all gather in the keyway over time. On outdoor locks, add pollen, sand, insects, and salt. Padlocks, gate locks, mailbox locks, and the cylinder on the garage entry door are the usual victims.
Signs of debris include a key that goes in most of the way and stops with a soft, spongy feeling, a key that enters with a gritty or scratchy sensation, and a key that comes out with visible dirt or dark smears on the blade. If a flashlight shows lint or dirt at the opening, the diagnosis is easy.
A cautious clean is usually enough. Shine a light into the keyway to see what is there. Compressed air in short bursts can blow out dust. A plain wooden toothpick or a thin plastic strip can lift a visible piece of lint near the opening, but do not poke into the lock deeply, because pushing debris further in makes it worse. Do not use a pin, needle, or metal pick, which can scratch the pins or push a stuck object deeper.
What to avoid spraying into the lock
The reflex to spray is strong, and the wrong product can make a sticking lock worse. General purpose penetrating oils and household lubricants are designed to creep into metal joints and leave a wet film. In a lock, that film catches dust. Over time it hardens into a paste that fouls the pins. The lock may feel better for a day and then be worse than before.
Cooking oil, petroleum jelly, and grease have the same problem and attract even more dirt. Silicone sprays in large amounts can foul the cylinder. Water displacing sprays sold for tools may help drive out moisture, but they leave residue that is not ideal for lock pins, and they are not intended for repeated use in a cylinder.
Better choices are a dry lubricant made for locks, applied in a tiny quantity, and compressed air to clear the dust first. If the lock has been exposed to road salt or sea air, corrosion may be involved, and spraying will not undo it. If you are unsure, it is better to do nothing than to flood the cylinder, because a technician can clean and service a lightly dirty lock far more easily than one filled with sticky residue.
- Avoid thick oils, cooking oil, and grease inside the keyway.
- Avoid soaking the lock with water displacing sprays more than once.
- Avoid blowing into the lock with your mouth, since moisture and breath can freeze in cold weather.
- Avoid using metal tools to dig out debris.
- Use only a small amount of dry lock lubricant, and only after the keyway is clean.
A bent, worn, or damaged key
Keys live a hard life. They are carried in pockets, dropped on pavement, used as pry tools, and left in car doors. A key that has been bent even slightly may enter a lock with difficulty or not at all, since the keyway tolerance is tight. A key that has been bent back to straight is weakened and may break the next time it is used.
Look at the blade along its length by holding it against a flat surface. A blade that rocks or does not lie flat is bent. Look for a rounded tip, burrs along the cuts, and a worn surface that looks shinier than the rest of the key. Burrs on a freshly cut copy can catch inside the keyway, which is why a new copy sometimes sticks until it is deburred.
Do not try to straighten a bent key by hammering or by squeezing it in a vise unless you are comfortable with losing it. A professional can often make a new key from the original or from the lock itself, which is better than depending on a damaged key. For car keys, the process may include programming a transponder chip, as explained on our page about how car key programming works.
Damaged pins and internal cylinder faults
If the key is correct, clean, and straight and still will not go in, the cylinder itself may be damaged. Internally, a pin can come out of position, a spring can break, or a part can shift and block the keyway. A pin stack that has been pushed out of line by a previous failed attempt to open the lock, or by an earlier broken key, can protrude into the keyway.
Forced attempts at entry leave marks. Look for scratches, gouges, and bent metal around the keyway opening, and a cylinder face that looks damaged or dented. A lock that was tampered with during a break-in attempt may no longer accept a key, and the owner may not realize until the next time they try to use it. If that sounds like your situation, see our page on lock repair after a break-in.
A cylinder with an internal fault generally needs to be taken apart or replaced. Taking it apart requires knowing how the particular lock is built, and getting it wrong can leave you with a pile of tiny parts and no working lock. That is a job for a trained technician.
Broken key fragments still in the lock
Sometimes the reason a new key will not enter is that part of an older key is still inside. A key may have snapped weeks ago, leaving a short piece that sat unnoticed behind the opening. Another key then goes in only part of the way and stops against the fragment.
Look in with a flashlight for a shiny edge or the end of a cut. If you can see the fragment, do not try to pull it with tweezers or pliers unless it is sticking well out of the keyway. A fragment pushed in or twisted can jam the cylinder more tightly. Extraction tools made for the job grab the fragment's cuts and slide it out without damaging the pins.
Our page on broken key extraction describes how a professional handles it, and the related page on a broken key in a car door covers the vehicle version. In many cases the fragment can be removed and the lock kept in use, with a new key cut afterwards.
Temperature, moisture, and outdoor locks
Weather matters. Cold can freeze moisture in the keyway, and a key that stops at the same depth every winter morning is a strong hint. Heat can expand metal slightly and make a marginal key tighter. Humidity and salt air speed up corrosion on pins and springs, which shows up as a gritty, rough feeling when the key enters.
Outdoor locks need regular care. A padlock on a gate should be turned so that the keyway points down, which helps keep rain out. A mailbox lock or a lock on a gas meter housing benefits from a quick clean and a dry lubricant at the start of each season. Our page on locks freezing in cold weather covers frost and ice specifically.
If the lock is a decade old or more and lives outdoors, plan for the possibility that it is simply worn out. Replacing an old outdoor lock is often more sensible than treating it every season, since the cost of a lock that fails at the wrong moment is far greater than the lock itself.
When to call a locksmith, and what to say
Call when the key is the right one and the keyway looks clean but the key still will not enter, when you can see damage to the cylinder, when a key fragment is inside, when you cannot get inside because of the problem, or when the lock protects something that matters and you cannot trust it. Do not wait until it fails completely, since a lock that will not accept a key is already failing.
On the phone, describe what you tried, what the key does (how far it goes in, whether it feels gritty or hard), what kind of lock it is, and where it is. Quotes are given by phone. A service call charge applies and is explained before dispatch. Complex jobs need an on-site visit, and the technician explains what is found before work begins.
A legitimate locksmith asks you to confirm that you own or control the property or vehicle. Have photo identification and something that ties you to the address or vehicle ready. Our guide on how to prepare for a locksmith visit lists the details. When you are ready, call and describe the problem, and we will talk through the safest next step.
Questions people ask
Why will my key only go in halfway?
Most often something is blocking the keyway, such as lint or a broken piece of an earlier key, or the key is bent or the wrong one. Stop pushing, remove the key, and look into the keyway with a flashlight. If you cannot see an obvious cause, have a professional check the cylinder before damage occurs.
Is it safe to clean a lock with a pin or needle?
It is better not to. Metal tools can scratch the pins and push debris deeper, and a tip that breaks off becomes a second blockage. A short burst of compressed air and a soft plastic or wooden pick for visible lint near the opening are safer. For anything deeper, a technician has the right tools.
My new copy of a key will not go in but the original does. Why?
The copy may have been cut on the wrong blank, or it may have burrs left from cutting that catch in the keyway. Slight differences in profile prevent entry. Take the copy back to be recut and deburred, or have a locksmith cut a new one from the original on the correct blank.
Can I use WD-40 to get a key into a lock?
It may help briefly, but general purpose sprays leave a wet film that collects dust and can foul the pins later. If you lubricate at all, use a small amount of dry lubricant made for locks after clearing debris. Heavy spraying often makes the lock worse over the following weeks.
What if the key went in but now will not come out?
Do not yank on it. Try wiggling it gently while applying slight pressure in and out, since a pin may be catching a worn cut. If it will not release, stop and call. Forcing it can snap the key and leave a fragment inside, which then needs extraction.
Could my lock have been tampered with?
It is possible if you see fresh scratches around the keyway, a damaged cylinder face, or if the lock stopped working after a break-in attempt. Contact the police if you suspect an attempt, and have the lock inspected. Do not keep forcing keys into a cylinder that may be damaged inside.
Describe the situation by phone and we will tell you what the job involves. Quotes are given by phone. Jobs that cannot be quoted without seeing them need a technician on site, and the service call charge is explained on the phone before anyone is dispatched.
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Written by Claude (AI) (AI) for 24/7 Locksmith USA.