Mitsubishi Immobilizer System Service Required: Causes & Fixes

If you are getting the Immobilizer System Service Required error, it means there is a communication error with the electrical steering lock, KOS (keyless operation system), or the ECM.

This error message is common with Mitsubishi vehicles driven in cold weather, usually -24°C. Once the message is triggered, the car goes into full security mode and cannot be bypassed unless the module is warmed up.

While you may see this message for many reasons, this article is compiled to help you diagnose and identify the symptoms and causes and recommend fixes to the error message.

What is Mitsubishi Immobilizer System Service Required?

The Mitsubishi Immobilizer System Service Required warning light indicates a faulty electronic immobilizer system. 

When this happens, the vehicle will refuse to start, and the security mode of your car is activated.  The warning message may be only temporary; in this case, turn the ignition to the off position, wait for a few minutes, and attempt to restart the vehicle. You can use the spare key if you have a spare key.

Furthermore, the immobilizer system is designed to recognize the vehicle’s key and authorize engine ignition. 

When you turn the ignition key, the immobilizer system transponder sends a unique code to the car’s control unit. The vehicle computer then checks this code against a list of approved codes, and the vehicle computer lets the engine start if the code matches. However, if a wrong code is found, the engine will not start, making it impossible to drive the car.

The Mitsubishi immobilizer gives the car an extra layer of protection, giving the owner peace of mind and making it less likely to be stolen. It is a very important way to keep thieves from trying to start the engine without the right key.

Causes of Mitsubishi Immobilizer System Service Required Warning

The Immobilizer System Service Required error message may be triggered under three main conditions:

  • There is a communication failure with the electrical steering lock, KOS, or ECM
  • Failure of the electrical steering lock caused by a P detection switch malfunction
  • When the power supply mode is turned on, but the keyless operation key reads that it is outside the car.
  • Other causes include:

Key-related Issues

A damaged or malfunctioning key may not be properly recognized by the immobilizer system. You should check the key for any visible damage; if there is any, the key must be replaced completely. 

In addition, confirm if the key is equipped with a functioning battery. Ensure the battery is strong enough. If needed, replace the battery with a functioning one. Sometimes, you may need to reprogram the vehicle’s immobilizer system key. 

Immobilizer System Malfunction

Faulty Antenna or Receiver: If the “Mitsubishi Immobilizer System Service Required” light comes on because the antenna or receiver isn’t working right, it means there’s a problem with the parts that receive and send messages between the key transponder and the immobilizer control unit (ICU). 

Defective Immobilizer Control Unit (ICU)

The ICU is the brain of the immobilizer system. It is responsible for processing signals from the key transponder and authorizing the engine’s start-up. 

Fixing a broken immobilizer control unit as soon as possible is important to ensure your Mitsubishi works well and stays safe. If you try to fix or change the ICU without the right knowledge and tools, you could cause more problems or compromise the car’s security. 

Battery or Electrical Issues

Weak or Dead Battery: A weak or dead battery in the key fob can result in communication issues with the immobilizer system. Replacing the key fob battery is a simple fix. This simply means you do not need professional assistance. 

Low Vehicle Battery

A low vehicle battery can also cause the immobilizer system to malfunction. If the car’s battery is low on power, it might not give the immobilizer system enough energy to work properly. 

This could cause problems with the communication and set off the “Mitsubishi Immobilizer System Service Required” warning. Charging or replacing the vehicle battery may be necessary.

Programming Glitch

Sometimes, a small glitch or mistake can happen in the programming, causing trouble with communication and a false warning sign. Several things, like software updates, electronic interference, or brief programming errors in the immobilizer system, can cause these problems. Resetting the system may fix such glitches in the car’s computer system.

Fixes for the Mitsubishi Immobilizer System Service Required

Fixes for the error message will depend on the identified causes. In this section, we shall recommend fixes based on identified causes above. They are as follows:

For immobilizer malfunction, Some fixes include:

  • Check Antenna and Wiring: Look for noticeable damage or loose connections. Fix or replace broken parts.
  • Address Interference: Make sure no electromagnetic sources or electronic gadgets are nearby that could interfere with the key transponder and immobilizer system signals. These can impair antenna and receiver performance.
  • Reset the System: Resetting the immobilizer system can fix temporary communication issues. Disconnect the battery and turn off the engine. Start the engine to reset.
  • Professional Inspection: If the issue persists or you need clarification of the warning’s source, contact an authorized Mitsubishi service shop or trained automotive expert. 
  • Replace Faulty Components: If the antenna or receiver fails an examination, replace it with original Mitsubishi parts. Authentic parts ensure compatibility and performance.

Someone on YouTube has shared a method for fixing the issue. You can try the following steps:

  1. Stand beside the car and press the panic button on the key fob (the red button).
  2. Close the car door and lock it.
  3. Walk away from the car, maintaining a distance of approximately 30 feet for about 10 minutes.
  4. Return to the car after the 10-minute wait.
  5. Use the key fob to unlock the car. If the light on the key fob illuminates, it indicates that the fob’s battery is still working fine.
  6. Attempt to start the car again by pressing the brake pedal and using the ignition or push-button start.


The Mitsubishi “Immobilizer System Service Required” warning indicates a potential issue with the vehicle’s security system. Ignoring this warning could result in starting difficulties and compromised vehicle security. 

If you encounter this warning message or experience symptoms related to the immobilizer system, you should seek professional assistance from a qualified Mitsubishi dealership or automotive expert.

  • Edmond Davis

    I'm Edmond Davis, an automotive expert with years of experience in vehicle repair, performance, and safety. I graduated from the University of Michigan with a degree in Automotive Engineering and have worked with major companies like Ford, GM, and Chrysler. I'm a trusted source of information for anyone looking to learn more about cars or improve their driving experience.

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