Troubleshooting Mitsubishi Servo: Resolving the AL16 Driver Alarm

Mitsubishi Servo systems are renowned for their reliability and precision, often deployed in industrial automation applications. However, like any sophisticated machinery, they are not completely free of glitches.

One such glitch, the AL16 driver alarm error, has been known to disrupt normal operations. This article provides an in-depth look into the problem and outlines a systematic approach to solving it.

Table of Contents

AL16 Error: What Is It?

In a nutshell, the AL16 error means there’s a hiccup in the communication between your servo motor and the encoder. When this error pops up, it’s the system telling you something is off. You’ll likely notice that your servo motor isn’t running as it should, and you’ll see the AL16 error on your driver screen.


  1. Servo motor not operating or behaving erratically
  2. AL16 error displayed on the driver screen

Quick check before further operation

Before you start disassembling anything, let’s make sure we’re actually dealing with an AL16 error.

  1. Is AL16 Showing on the Driver Display? Pretty straightforward, check the driver screen.
  2. Logs Show Anything Weird? Look through the error logs for discrepancies related to the encoder or motor position.
  3. Is the Encoder Cable Okay? A quick visual check to make sure the cable isn’t visibly damaged.

Fixing the AL16 Error: Step-by-Step

First, Reset Your System

  1. Power down your servo drive and controller.
  2. Wait about 10 seconds.
  3. Fire everything back up and see if the error is gone.

Next, Inspect and Secure the Encoder Cable

  1. Turn off the system for safety.
  2. Disconnect and then reconnect the encoder cables. Make sure they’re snug.
  3. Turn everything back on.

Double-Check Your Settings

  1. Go into your driver’s settings via the controller.
  2. Verify that your encoder settings align with the manufacturer’s specifications.

Finally, Run a Quick Test

  1. Initialize the servo motor.
  2. Execute a simple move.
  3. Keep an eye out for the AL16 alarm. If it’s gone, you’re good to go!

What to Do If the Error Remains

If you’ve tried all of these steps and the AL16 error is still there, it might be time to consider professional repair or even replacing some of your components.


Congrats! You’ve hopefully solved the AL16 error and are back to smooth operations. But imagine a future where your servo system could self-correct these issues automatically. With the advances in Industry 4.0 and IoT, that day may not be too far away!

If you’re in need of high-quality, original Mitsubishi products (from PLCs and servos to HMIs) look no further than Kwoco.

Our products are guaranteed to be top-notch in quality. But what sets us apart is our dedicated team of professional engineers, always ready to assist you in solving any technical challenges that may arise.
Choose Kwoco for a seamless, reliable automation experience. Visit our website to explore our product range and services today!

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