What Is a Key Lock Box?

A key lock box (also called a combination key safe or realtor lockbox) is a small, weather-resistant box designed to hold a spare key. It attaches to a door handle, fence post, or wall-mounted bracket and opens only when the correct code is entered. They are widely used by:

• Real estate agents giving buyers access to listed properties
• Vacation rental and Airbnb hosts managing guest check-ins
• Homeowners leaving keys for family members, cleaners, or contractors
• Caregivers and medical personnel needing reliable home access

Most residential lockboxes use a 3- to 5-digit rotating dial or push-button combination. Understanding which type you have is the first step before attempting any code change.

Types of Key Lock Boxes

There are three main lock box mechanisms, each with a slightly different reset process:

Rotating Dial (Combination) Lock Box

These feature a set of numbered wheels that you spin to align with the correct digits. Common brands include Master Lock and Kidde. They are simple, battery-free, and highly durable.

Push-Button (Directional) Lock Box

Instead of numbered dials, these use four directional buttons (Up, Down, Left, Right) entered in a specific sequence. The Master Lock 5400D series is a popular example. The code can include repeated presses of the same button.

Electronic / Smart Lock Box

These use a keypad, touchscreen, or Bluetooth app to manage access. Brands like Supra, SentriLock, and August offer models that allow remote code changes from a smartphone. The reset procedure usually involves a companion app or a dedicated admin PIN.

How to Change a Key Lock Box Code — Step-by-Step

Below are instructions for each common type. Always start by opening the lockbox with the current code before attempting a reset.

Rotating Dial Lock Box

1. Open the shackle with your current code. Align the dials to your existing combination and pull the shackle upward to open the box.
2. Locate the reset button or tab. Look on the inside of the door or on the back of the lock for a small circular reset button, often requiring a pen or paperclip to press.
3. Press and hold the reset button. While the shackle is open, press and hold the reset button firmly. On some models, you push the shackle down while pressing.
4. Set your new code. While holding the reset button, rotate the dials to your desired new combination.
5. Release and test. Release the reset button, close the shackle, and scramble the dials. Re-enter your new code to confirm it works before storing the key inside.

Push-Button (Directional) Lock Box

1. Enter your current code to open the box. Press the directional buttons in the correct sequence until the door opens.
2. Press and hold the RESET button. With the door open, locate and press the small reset button on the interior of the lock (some models require a pinhole press).
3. Enter your new code sequence. While holding RESET (or immediately after releasing, depending on the model), enter your new button sequence.
4. Press RESET again to confirm. Many push-button models require a second press to save the new code.
5. Close the door and test immediately. Close the lock box, then enter your new sequence to verify the change was saved correctly.

Electronic / Smart Lock Box

1. Open the box using your current PIN or app. Authenticate via the keypad or your Bluetooth-connected smartphone app.
2. Navigate to the settings menu. On the keypad, enter a dedicated admin command (often *[current code]# or a brand-specific sequence). In an app, go to Settings → Change Code.
3. Enter your new PIN and confirm. Type the new code, then re-enter it when prompted to confirm. Some models require the confirmation within 30 seconds.
4. Wait for the confirmation signal. The device will beep, flash green, or display a confirmation message. Your new code is now active.
5. Lock and test. Close the box, wait for it to lock, and verify your new PIN grants access.

Important: Never store the key inside the box before confirming your new code works. Testing with an empty or temporary key first eliminates the risk of a lockout.

Brand-by-Brand Reference Guide

Different manufacturers have slightly different reset procedures. The following overview covers the most common residential lock box brands.

Master Lock 5400D (Push-Button)

Open the box, then hold the recessed RESET tab (a pen tip is helpful) and enter your new directional sequence. Release the tab to save. The shackle must be in the open position throughout the entire process.

Master Lock 3-Dial (Rotating Dial)

Pull the shackle up to open, press the reset button inside the compartment, set your new dial combination, then release. The shackle must remain pulled up during the full reset procedure.

Kidde AccessPoint (Push-Button)

Open the box, press the CHANGE CODE button, then enter your new 4-digit code twice. Both entries must match within 10 seconds for the change to register.

Supra iBox BT LE (Electronic / Bluetooth)

Changes are made via the SupraWEB portal or the iBox companion app under Settings → Change Combination. Agent-level app credentials are required to access this menu.

Yale Y500 (Electronic)

Enter your current code followed by #, then your new code followed by #, then confirm the new code followed by # once more. The LED flashes amber twice to confirm a successful change.

What to Do If You've Forgotten the Current Code

Losing the existing combination before resetting is more common than you might expect. Here are the recommended approaches depending on your situation:

Try Common Factory Default Codes

Many lock boxes ship with a default code such as 0000, 1234, or a code printed on the original packaging. If the lock was never changed from factory settings, these are worth trying first.

Contact the Manufacturer

Most major brands (Master Lock, Kidde, Yale) have a customer service line that can assist with recovery — especially if you have proof of purchase. Some manufacturers require you to mail in the unit for a factory reset.

Use a Locksmith

A licensed locksmith can often manipulate the dials of a mechanical lock box to identify the combination without damage. This typically costs between $30 and $100 and is faster than replacement in most cases.

Replace the Lock Box

When all else fails, replacement is the most cost-effective option. A quality residential lock box typically ranges from $15 to $60, making replacement financially sensible if recovery attempts have failed.

Legal reminder: Only attempt to open or reset a lock box that you own or have explicit authorization to access. Tampering with a lockbox without permission may be illegal in your jurisdiction.

Choosing a Strong New Code

The code you choose is just as important as the reset process itself. A predictable combination undermines the security the lock box is meant to provide. Follow these guidelines when selecting a new code:

• Avoid sequential numbers — combinations like 1234, 2345, or 9876 are the first guesses an intruder will try.
• Avoid personal dates — birth years, anniversaries, and addresses are easy to guess with minimal research.
• Use all available digits — if your box supports a 5-digit code, use all five rather than a shorter sequence.
• Avoid repeated digits — codes like 1111 or 2222 offer minimal security.
• Change codes regularly — for Airbnb hosts and property managers, changing the code after each guest or contractor visit is best practice.
• Record it securely — store your code in a password manager, not in a text message or sticky note near the box.

Maintaining Your Key Lock Box

A lock box exposed to outdoor conditions requires periodic maintenance to remain reliable. Here is what to watch for:

Lubrication

Apply a small amount of dry PTFE (Teflon) spray or graphite powder to the dials or buttons every 6–12 months. Avoid WD-40 and oil-based lubricants, which attract dust and can cause stiffness over time.

Weather Protection

Inspect the rubber seal around the door regularly. If the seal is cracked or missing, moisture can damage the key inside and corrode the internal mechanism. Replacement seals are inexpensive and widely available.

Battery Checks for Electronic Models

Most smart lock boxes will give a low-battery warning before failing completely. Change batteries at the first warning rather than waiting, to avoid a lockout during a critical moment.

Shackle Inspection

Examine the shackle periodically for signs of wear, rust, or attempted tampering. A shackle that no longer locks firmly should be replaced immediately, regardless of whether the combination mechanism still works.

Frequently Asked Questions

Can I change my lock box code without opening it first?

In most mechanical lock boxes, no — you must open the box using the current code before a reset is possible. The reset mechanism is typically located inside the box or requires the shackle to be in the open position. Electronic lock boxes, however, sometimes allow code changes via a companion app without physically opening the box.

How many digits should my lock box code be?

Most residential lock boxes support between 3 and 5 digits. A 4- or 5-digit code is strongly recommended. A 4-digit numeric code has 10,000 possible combinations, while a 5-digit code has 100,000 — significantly harder to brute-force in an opportunistic theft scenario.

How often should I change my key lock box code?

For vacation rentals and managed properties, change the code after every guest checkout or contractor visit. For personal use, changing the code every 3–6 months is a reasonable cadence — or immediately following any security concern, such as a lost key or a dispute with an access holder.

My reset button doesn't seem to work — what should I do?

First, confirm the shackle is fully in the open/up position — most reset buttons are disabled when the shackle is closed. If the shackle is open and the button is unresponsive, the internal mechanism may be seized due to dirt or moisture. Try applying dry graphite lubricant and working the dials or buttons several times. If the problem persists, contact the manufacturer or consider replacing the unit.

Is it safe to use a lock box for an Airbnb property?

Yes, when used correctly. Choose a lock box rated for outdoor use, install it on a solid fixed surface, use a strong non-guessable code, and change the code between every guest stay. For higher-security needs, consider a smart lock box with temporary access codes or a full smart lock that integrates with your Airbnb platform.

Final Thoughts

Knowing how to change a key lock box code takes only a few minutes once you're familiar with your specific model, and it's one of the most impactful steps you can take to maintain reliable home access security. Always test the new code before closing the box, choose a combination that's genuinely random, and establish a routine to refresh codes whenever access changes hands.

Whether you're managing a rental property, coordinating care for a family member, or simply updating an aging combination, the process is well within reach for any homeowner — no locksmith required.