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Error code reference

Denso Air Conditioner Error Code LOCKED

Key lock mode is active

Denso codesDenso air conditioner codes

Key lock mode is active — control panel buttons are locked.

First step from the service manual

Press ENTER and SET CLOCK buttons simultaneously for 5 sec to cancel key lock mode.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What LOCKED means on a Denso air conditioner

The LOCKED indicator on a Denso air conditioner signals that the key lock mode is currently active. Key lock mode is a built-in control panel feature that disables all front-panel buttons to prevent unintended changes to the unit's operating settings. This is a software-level lock state managed by the control board's firmware, not a fault or hardware failure. The unit continues to operate normally in its current mode while the lock is engaged; only manual button input at the panel is blocked.

Key lock mode is typically engaged or accidentally triggered through a specific button combination on the control panel. On Denso units, pressing the ENTER and SET CLOCK buttons simultaneously for approximately 5 seconds toggles this mode on or off. Because these buttons may be pressed inadvertently during routine cleaning, unit adjustments, or accidental contact, the lock state can appear without the user deliberately enabling it.

No components are damaged or malfunctioning when LOCKED is displayed. This is entirely a control interface condition. Once the key lock is deactivated using the correct button sequence, full panel functionality returns immediately. If the lock cannot be cleared with the standard button combination, the issue may point to a stuck or unresponsive button on the control panel itself, which would require physical inspection of the panel assembly.

Source: manufacturer service documentation.

Common causes of LOCKED

  1. 01

    Accidental button combination press

    Wiring / connection

    The most frequent cause is an unintentional simultaneous press of the ENTER and SET CLOCK buttons, which can happen during cleaning, routine adjustments, or accidental contact with the panel.

  2. 02

    Deliberate key lock activation

    Wiring / connection

    A household member or facility manager may have intentionally enabled key lock mode to prevent settings from being changed, without informing other users.

  3. 03

    Cleaning contact with control panel

    Wiring / connection

    Wiping down the control panel surface with a cloth can inadvertently activate the lock if pressure is applied to multiple buttons at once during the cleaning process.

  4. 04

    Stuck or intermittently shorted control panel button

    Part replacement

    If the LOCKED state cannot be cleared with the standard button sequence, a physically stuck or internally shorted ENTER or SET CLOCK button may be holding the lock condition active. Inspect the buttons for debris, warping, or damage.

  5. 05

    Control board firmware glitch

    Wiring / connection

    In rare cases, a momentary power fluctuation or firmware anomaly can cause the control board to enter and retain key lock mode. A full power cycle by shutting off the unit at the breaker for several minutes may reset the state if the standard button sequence does not respond.

See the test procedure for each cause

Frequently asked questions about LOCKED

What does LOCKED mean on a Denso air_conditioner?
LOCKED means the control panel's key lock mode is active, which disables all front-panel buttons to prevent unintended setting changes. The unit itself continues to operate normally in its current mode. This is not a fault code and does not indicate any component failure. It can be cleared by pressing the ENTER and SET CLOCK buttons simultaneously for 5 seconds.
How do I fix the LOCKED condition on my Denso air conditioner?
Press and hold the ENTER and SET CLOCK buttons at the same time for approximately 5 seconds. This toggles the key lock mode off and restores full control panel functionality. If the buttons do not respond or the lock does not clear, check whether any panel buttons are physically stuck, and consider cycling power to the unit at the breaker before attempting the button sequence again.
Is it safe to keep using my Denso air conditioner while it shows LOCKED?
Yes, the unit is safe to operate while in key lock mode. The air conditioner continues to run normally at its current settings; only manual panel input is restricted. There is no risk of equipment damage or safety hazard associated with the key lock state.
Will resetting the unit clear the LOCKED condition on a Denso air conditioner?
A power cycle, such as turning off the breaker for several minutes and restoring power, may clear the key lock state if the standard button sequence is not working. However, the correct and intended method is the simultaneous ENTER and SET CLOCK button press held for 5 seconds. A power reset should be treated as a secondary troubleshooting step.
How much does it cost to repair a Denso air conditioner stuck in LOCKED mode?
In most cases there is no repair cost at all, since the LOCKED condition is cleared through a button sequence and requires no parts or technician visit. If a stuck or faulty control panel button is preventing the lock from clearing, a service call and control panel button or panel assembly replacement could range from around $75 to $250 or more depending on parts availability and labor rates in your area.

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