What causes door locks to stop working?

Door locks stop working for several reasons, including worn or damaged components, misalignment of the strike plate, weather-related sticking, and power or electronic failures in modern locks.

This article examines the common causes, how to recognize symptoms, and practical steps to troubleshoot, repair, or replace locks, with guidance for homeowners and property managers alike.

Mechanical wear and misalignment

Traditional mechanical locks rely on precise alignment and smooth operation of moving parts. When these elements degrade or shift, the lock can fail to turn, jam, or fail to retract the latch.

• Worn or stripped key cylinder that won’t turn or grips poorly


• Damaged or worn internal pins, springs, or levers causing sticking or inaccurate engagement


• Jammed latch, bolt, or deadbolt from dust, debris, rust, or corrosion


• Misaligned strike plate or strike box preventing full engagement of the bolt


• Loose mounting screws or warped doors that shift the lock body out of alignment


• Broken key or a bent/damaged key that won’t insert properly

Regular maintenance—cleaning the keyway, replacing worn cylinders, tightening screws, and ensuring the door remains square—can prevent many mechanical failures.

Electrical and smart lock failures

Electronic components introduce new failure modes. Power, firmware, and connectivity issues are among the most common causes of non-responsive locks.

1. Battery depletion or dead battery in wireless or Bluetooth-connected locks


2. Weak motors or actuators that can’t retract the bolt


3. Damaged or loose wiring in keypad, lever, or interior electronics


4. Outdated firmware or software glitches affecting lock behavior


5. Connectivity problems with hubs, apps, or cloud services (Bluetooth, Wi‑Fi, Zigbee/Z-Wave)


6. Incorrect user permissions or security settings locking you out

In most cases, replacing batteries, updating firmware, and re-pairing devices resolves many electronic failures. If problems persist, consult the manufacturer or a licensed locksmith to avoid compromising security.

Environmental and installation factors

Environmental exposure and installation quality can undermine lock performance over time. Temperature swings, moisture, and improper fit are common culprits.

• Freezing temperatures and ice buildup that freeze moving parts


• Rust, corrosion, or pitting from moisture, salt spray, or humidity


• Dirt, dust, or lint clogging the keyway or lever mechanism


• Door warp or frame settlement that misaligns the strike plate


• Improper installation, mis-sized hardware, or aging fixtures

Addressing environment and fitment issues—such as weatherproofing, rust treatment, and re-aligning the strike plate—can restore operation and extend lock life.

How to diagnose and fix

A systematic approach helps identify the root cause and determine whether a repair is feasible or if replacement is warranted.

1. Test mechanical operation with the appropriate key or thumb-turn while the door is open to identify whether the issue lies with the cylinder, knob/lever, or latch.


2. Check power sources for electronic locks: replace batteries with the recommended type and verify all connections are secure.


3. Inspect alignment: verify the bolt engages the strike plate smoothly; tighten screws and adjust the strike plate position if necessary.


4. Clean and lubricate moving parts judiciously: use graphite powder or a silicone-based lubricant; avoid oil-based sprays that attract dirt.


5. Inspect for debris, corrosion, or damaged components and address as appropriate or replace worn parts.


6. Test the lock after each fix and monitor for consistent operation; if issues persist, consider professional evaluation or replacement.

Tip: For electronic or smart locks connected to a broader security system, consult the user manual and the manufacturer’s support portal for device-specific troubleshooting and warranty coverage.

Maintenance tips to prevent future failures

These preventive steps are designed to reduce future lockouts and extend the life of both mechanical and electronic hardware.

• Regularly replace batteries in smart locks, following the manufacturer’s recommended schedule


• Lubricate moving parts with graphite powder or a silicone-based lubricant; avoid petroleum-based oils


• Keep strike plates aligned and screws tight; ensure doors and frames remain square


• Weatherproof the housing and treat exposed metal to resist rust and corrosion


• Keep spare keys and consider a mechanical override or hybrid lock to ensure access during electronic downtime

Conclusion: Routine maintenance and timely component replacement are the best defenses against unexpected lock failures.

Summary

Door locks stop working for a blend of mechanical wear, misalignment, environmental stress, and electronic failures. By recognizing the likely causes, performing methodical diagnostics, and applying appropriate maintenance or professional service, property owners can prevent most lockouts and maintain secure access. Always prioritize safety and consider professional help when dealing with high-security or complex smart-lock systems.

How much should it cost to replace a door lock actuator?

On average, a door lock actuator will cost between $125 and $250 for the part alone. Some models can be significantly higher or lower, though. If you need a mechanic to do the job for you, expect them to charge between one and two hours of labor, which could be a couple hundred dollars or so.

Should you put WD-40 in a lock?

No, you should not put WD-40 in a lock because it's a solvent, not a long-term lubricant, and will attract dirt and dust, causing the lock to become gunked up and potentially fail. Instead, use a dry lubricant like graphite powder or a silicone-based spray to keep locks working smoothly. 
This video explains why you should not use oil or graphite in a lock and suggests alternatives: 59sMr. LocksmithYouTube · Jun 5, 2020
Why WD-40 is a poor choice for locks

• It's a solvent: WD-40 is designed to clean and penetrate, not to lubricate a lock's delicate internal parts. 
• It attracts dirt: The oily residue left behind attracts dirt and dust, which can create a gritty paste that clogs the lock. 
• It can cause damage: This residue can cause the lock's internal mechanisms to wear down and eventually fail. 
• It removes existing lubricant: It can strip away any existing lubricant inside the lock cylinder. 

What to use instead

• Graphite powder: This is a dry lubricant that won't attract dirt and is a top recommendation from locksmiths for a reason. 
• Silicone-based spray: Many new products are designed for locks and can provide a protective, slick barrier without attracting grime. 
• Other dry lubricants: Look for products specifically labeled as "lock lubricant" or "dry lubricant". 

This video demonstrates how to fix a sticky lock using a silicone-based lubricant: 58sMr. LocksmithYouTube · May 22, 2024

Why is my lock not turning from the outside?

Quick fix: To attempt a simple fix, apply a dry Teflon lube or powdered graphite to the keyhole to unjam the lock. Exterior doors may require a commercial lock cleaner that you spray into the keyhole to dissolve debris or dirt, and you can also try compressed air to dislodge dirt inside deadbolts and keyed locks.

Why did my lock suddenly stop working?

Lock is either wearing out or needs to be lubricated. Lube it (cheapest and easy to do yourself - just have paper towels or a rag handy to catch drips) or replace it (fairly inexpensive if you can read up and do it yourself).