Your car immobilizer is an essential component that prevents car theft from stealing your car unless they have the original car key with the keyfob. Usually, car theft steals cars by hot-wiring them. But with the immobilizer system in place, it is impossible for them to steal the car by just hot-wiring it. Car manufacturers integrate this security feature to prevent car theft.
However, some situations may prompt you to remove the immobilizer system from the ECU. You will learn how to remove immobilizer from ECU and why someone may want to remove it in the first place.
What is an immobilizer, and why someone might want to remove it?
An immobilizer is a security feature in cars that prevents anyone who does not have the right key from starting your car. Hence, it becomes very hard for anyone without the right key to steal your car. The right key is an authorized keyfob with a transponder chip that reads and transmits a passcode.
When you insert the authorized key into the ignition, the transponder chip transmits a code to the engine control unit. Then, the immobilizer will authenticate the code in the ECU and the one from the transponder chip. If it corresponds with the code in the system, the car will start. But if it doesn’t, the ECU will not send fuel into the engine, nor will it activate the ignition circuit.
In some cars, the immobilizer system features an alarm, which lets you know when someone attempts to start your car with the wrong key. However, the immobilizer is different from an alarm system. Alarms only notify you when someone wants to steal your car. It doesn’t prevent them from stealing it. On the other hand, immobilizers prevent theft from stealing your car by preventing fuel and ignition mobilization.
However, you can remove the immobilizer system so you can start your car without the ECU and transponder chip sending and reading the code in the vehicle. But why will someone ever want to remove this security system?
The common reason people remove the immobilizer system is when it starts malfunctioning. If you see the “immobilizer active” message on your information display center, it means the immobilizer has not recognized your car key. You can try removing and reinserting the key again. If it continues, it means the immobilizer system has malfunctioned.
So, people typically remove the immobilizer to eliminate immobilizer problems such as trouble unlocking or starting the car. Another reason why you may want to remove the immobilizer is if you want to upgrade the system and add new security systems. Also, if an electrical surge damages the ECU, you may want to remove the immobilizer for the new ECU to work on the car.
Another common reason is when you lose your original key and want to get another key. You can decide to remove the system entirely if you don’t want to visit your dealership to configure the new keyfob.
But what causes immobilizer failure? Car immobilizer can fail due to a dead keyfob battery. But if the keyfob is working fine, check the immobilizer engine wiring. You could see corroded or damaged wiring, which shows there is an issue with the immobilizer control module.
How to remove immobilizer from ECU
Before proceeding with the step-by-step guide on how to remove immobilizer from a car, you’ll need some basic tools.
Tools and Items Needed
- Plastic trim removal tool
- Flat and start head screwdriver
Whether you are searching for how to remove immobilizer from an ECU on Honda or how to remove immobilizer from a VW ECU, this guide will walk you through it. It will guide you on both factory-fitted and aftermarket immobilizer removal processes. However, since cars differ from each other, I’ll be explaining the process on a Mazda 93MX-5.
Step 1: Remove the steering column cover
Get into your vehicle and sit on the driver’s seat. While sitting there, lower the steering column so you can access all the components and carry out the work. Remove the cover so you can access the wiring harness that connects to the immobilizer.
Step 2: Locate the immobilizer wire
Locate the immobilizer wire by tracing the wiring harness to the immobilizer unit. Ensure you do this carefully to avoid mistaking another wire for an immobilizer wire. The wiring harness that goes to the immobilizer is often tied up.
Step 3: Remove and snip out the wire
Trace the wire to its fuse and disconnect it. If it is stuck, get a side cutter to snip it off. After snipping off the wire, you will see the ME6 immobilizer. Get a Stanley blade and cut the insulator around the wire.
Step 4: Disconnect the ignition switch
Locate and unplug the permanent 12-volt feed that transmits electrical voltage to the ignition switch when you insert a key into the ignition. The reason for this is so that you can gain enough room to work on the immobilizer.
Step 5: Hold the trigger wire
You should be facing the trigger wire that prevents electrical voltage from getting into the immobilizer until you program the dongle in the receiver. Snap off the two earth piles to 12 mils so you can see the large fuse box. Take off the battery and short the two wires on the ignition connector.
This is all you need to remove your car immobilizer. It is that simple. Now, follow the reverse process and fix everything you removed earlier.
Alternatively, you can use the OBD2 immobilizer bypass approach to remove the immobilizer. An OBD2 (Onboard diagnosis) immobilizer bypass can allow you to use a key without a transponder. This approach allows you to bypass the immobilizer by using a high-end scan tool.
Removing your car immobilizer can have safety, legal, and security implications. Hence, you should take all precautions when removing your immobilizer. They are installed for security purposes, and disconnecting them may attract car theft. Here are the safety and security precautions you should take.
Remove the negative battery terminal to avoid shorting the ECU
Wear gloves and googles
Use the right tools to prevent breaking the plastic clips
Record the connections before removing any wire so you can put them in order after the removal
If you have been reading to this point, you have seen the simplified guide on how to remove immobilizer from ECU. When you finish removing the immobilizer, test the vehicle to confirm it is no longer working. Try starting the car with a spare key without a transponder chip and see if it will start the car. If it starts the car, you have successfully removed the immobilizer.
However, there is another method that involves soldering out the immobilizer from the engine control module. This method is not a DIYer approach. Hence, I recommend you leave it for a mechanic.