About Disconnecting Check Engine Lights

Disconnecting Check Engine Lights

Check Engine Warning Light

Unfortunately, disconnecting check engine lights is against the law, because it’s considered tampering with the factory emission control system.

If you do this in states with emission system testing they will be able to easily detect a disconnected engine warning light. Let me tell you how and why they do this.

The federal government in compliance with the clean air act has integrated the dreaded check engine light into the vehicle’s computer network via hardwired components and communication modules.

If you disconnect it you’re disabling the bulb check function as well. The bulb check is when the lamp is turned on behind the check engine light symbol to verify proper operation. This happens every time the key is on and the engine is not running.

In other words this self test lets everybody know its not working right. Why should you care if people know? Most areas have state inspections or smog check points that verify proper operation of the check engine light bulb test function.

If you have disconnected it you will be in violation of the clean air act and fail your state inspection. Technically the person that disabled the light could be fined. It use to be a thousand dollars, but I’m not sure how much it is today or how often the penalty is enforced.

How to Disconnect the Check Engine Light

Auto Facts repair manuals
Auto Facts Repair Manuals

Regardless of penalties some people still want to know how to disconnect check engine lights. It’s become a very difficult procedure to accomplish and it differs between car makers and model years. For this reason seeking out model specific instructions is the way to go.

You can sometimes find this in dedicated forums, but a complete PDF service manual  a better place to obtain this information. As an example, disabling the check engine light would require you to disassemble the dash and remove the instrument cluster.

And then you could remove the bulb from the socket or open the printed circuit connection. However, on most late model vehicles this is a difficult task to complete and might require special tools like security torx head sockets. Also on many models when you remove the check engine light bulb your computer that handles the air fuel mixture will go into a backup mode.

Mechanics call this the limp home function. This will cause poor gas mileage, lack of power and other symptoms that will make you want to go back to staring at the light. In essence your computer is monitoring the proper operation of the check engine warning and its bulb.

Technicians call the red or amber warning an MIL or (Malfunction Indicator Lamp). The good news is that it can be easier to repair the malfunction than it is to disconnect the light. The first step in the diagnostic procedure, in most cases, is clearing the code and see if it returns. Often an intermittent problem will trigger the light and it stays on until you clear it.

The U480 scanner I have above is the cheapest way of clearing codes that I’ve seen. I don’t own this device, but the reviews state it works as advertised. I recommend before you clear the codes that you write the 5 digit numbers down. This way if the check engine light comes back on you can see if it is the same code.

Don’t Disconnect the Check Engine Light

Innova 3040G Scan Tool

Believe it or not, the check engine light is your friend. It’s there to notify you that your car is suffering from either a minor or a major malfunction.

Over-riding the light is not only against the law, it is counter productive to a vehicle’s long-term health. Learning to fix check engine light malfunctions can be a rewarding experience.

On this website I supply information on how to accomplish this repair. Visit the resetting check engine light information page for tips on how to retrieve the failure code and repair the problem.

Also visit the DIY driveway page for online repair tips for bringing professional results home to your driveway. I have learned over the years that when you try to cheat the system you wind up putting in more time and effort then if you properly fix the auto repair problem in the first place.

About Disabling the Service Warning

I am sorry if you came to this page for the exact procedure on how to remove the check engine light. Don’t be mad, because as a certified ASE master technician I would be subject to at least a $1000 fine and penalties.

exhaust system diagram
Exhaust System Diagram

However, I’m not sure what the fines are today for providing this information, but I know it’s not worth it. It is against the law to not only disable the engine light, but to modify any part of its computerized emission system.

These actions fall under the category of tampering. This would include removing a catalytic converter and installing a test pipe. Many feel it’s a good idea to leave things alone, help improve air quality and keep your vehicle running as per its design intent.

If a check engine light is on, this is the car’s way of reaching out to you. It indicates a problem with the computer controlled fuel management or emissions system. Can you afford a little more then the $20 u480 mentioned above?

If so I recommend taking a look at the Innova 3030g. This scanner gives you room to grow and some advanced features. You can’t read the information stream or monitor conditions at the time of the fault, but the trouble codes are displayed with the full definition.

This means you don’t have to start hunting down what the code number stands for as with the U480. The 3030 also displays emission status which is what many States look at for pass or fail when performing smog and emission testing. Overall the price is good for the features and diagnostic capabilities included.

This next link takes you to one of the most popular pages on this site. Learn how to turn off check engine lights without a scanner. See the auto scan tools I own and more reasons to forget about disconnecting check engine lights and just fix the problem.

More information about the PDF service manuals including a video of how to fix cars with it is available below. See why these service manual program  documents remain a go to guide for online information seekers.

Up next is the homepage for this automotive website. Learn more about the mechanic that built it and why he answers questions about cars.