Check Engine Light Is on But No Codes (How to Fix it)

Your dashboard’s Check Engine Light is a sign that something is wrong when it comes on. In most situations, you would get out your code scanner and determine the source of the problem. So, what do you do if you can’t read any diagnostic codes that would otherwise tell you what the issue is?Check Engine Light Is on But No Codes

There are reasons why the Check Engine Light might be on even when no codes are present, even though it is a rare occurrence. Well, in this article, you’ll get to know the reasons why your check engine light is on but no code is visible. Also, we’ll be discussing if you should drive and how you can fix it.

So, let’s get started!


Why is the check engine light on but no visible error code?

Here are the most possible reasons why your check engine light is on but no codes:

  • Fault with the Code Scanner.
  • Scanner Port Contaminated.
  • Problem from User.
  • Electrical Short.
  • There’s a Blown Fuse.

Fault with the Code Scanner

Each code scanner is unique. There are many inexpensive diagnostic scanners on the market that can read the most basic codes, but they won’t offer you all you need for the transmission or emissions system. Furthermore, if you decide to get a free code scan at a nearby auto parts store, the staff members won’t be using an expensive diagnostic device. In its place, you receive a basic scan that might not include the predefined codes.

Scanner Port Contaminated

The OBD2 scanner is plugged into the proper port under the dashboard when you’re ready to utilize it. The connection itself may be problematic if the scanner isn’t functioning or extracting codes. Check the OBD port to determine if any debris or dust has gotten into the connector. Fortunately, you should only need a few seconds to complete this quick fix.

Problem from User

There’s a chance you missed anything even though you may believe you have automotive diagnostics down pat. Despite the code reader being a straightforward tool to use, you can’t rule out the possibility that you made a mistake. Reread the owner’s manual for your scan tool in a moment. No matter how simple the instructions may seem, always follow them. It’s conceivable that you missed something simple.

Electrical Short

It’s unlikely, but not impossible, that an electrical short is the source of your problems. A short somewhere in the system could cause power to leap to the light, forcing it to turn on. Without turning the engine on, you can check to see if this is the case by turning the key to the on position. After a few seconds, the light ought to turn off. If it doesn’t, there might be a shortage in the system.

There’s a Blown Fuse

You might consider throwing away the OBD2 device if nothing is reading while the code scanner is plugged into the device’s port. You should wait before getting rid of it because a blown fuse could be the issue. Just like the other electrical components in your car, the engine control module (ECM), electronic control unit (ECU), and powertrain control module (PCM) all operate off of fuses. If the fuse blows, the necessary component cannot receive juice. Even if there is no genuine malfunction, the light may nevertheless turn on. For information on which fuses you should check, consult the owner’s manual.

Is it safe to drive the car?

Driving a car with the Check Engine Light on but no codes is normally safe. If the computer system of the car doesn’t have any diagnostic fault codes, it can be a temporary or small problem. To guarantee optimum performance and stop potential problems from getting worse, it is still advised to get the issue identified and fixed by a skilled mechanic as soon as possible.

How can you fix the check engine light without code?

Check Engine Light Is on But No Codes

Look at the code scanner first before doing anything else. Are you utilizing the appropriate scanner, and can it read a variety of codes? The moment may have come for you to get a high-quality scanner if you haven’t already. Of course, there is also a chance that the scanner is broken.

To check if it is functioning properly, test it out on a different vehicle. If not, it needs to be replaced. The port where you are plugging it in should also be checked. Compressed air can be used to clear out any material that may be obstructing the connection.

Checking for blown fuses would be your next course of action. The owner’s manual contains information about fuse placement. Find the fuse that powers the ECU, ECM, or PCM, and determine whether it has blown.

If this is the case, changing the fuse should only cost a few bucks, and the Check Engine Light should go away. Anything more complex than these straightforward repairs might call for an expert. Take it to the shop for additional inspection if you are unsure how to locate an electrical fault.

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Why do I have a check engine light on but no codes?

There are a few possible reasons why the check engine light may be illuminated without any diagnostic trouble codes (DTCs) being stored:

  • The issue triggering the light may be intermittent, meaning it occurs sporadically and may not be present when the vehicle’s computer is scanned.
  • The code reader or scanner being used may not be able to retrieve all the codes stored in the vehicle’s computer. Consider using a professional-grade scanner or visiting a mechanic for a more accurate diagnosis.
  • There could be an electrical or computer problem preventing the codes from being stored or retrieved properly. This is relatively rare but may require specialized diagnostic tools to identify.

Can the check engine light come on and nothing be wrong?

Yes, it is possible for the check engine light to come on even if there doesn’t appear to be anything wrong with the vehicle. In some cases, it could be due to a faulty sensor or a temporary glitch in the vehicle’s computer system. However, it’s still important to have the vehicle checked by a professional to rule out any potential underlying issues.

What if the engine light comes on but the car runs fine?

If the check engine light comes on but the car is running fine, it could indicate a minor issue that doesn’t immediately affect the vehicle’s performance. However, it’s crucial not to ignore the light, as even seemingly small problems can develop into more significant issues over time. It’s best to have the vehicle checked by a professional to identify and address the underlying cause.

What is the first thing to check when the check engine light comes on?

When the check engine light comes on, the first thing you can do is check the gas cap. A loose or improperly sealed gas cap can trigger the check engine light. Ensure that the gas cap is tightened properly, and if it’s damaged, consider replacing it. After checking the gas cap, it’s still recommended to have the vehicle inspected by a professional to determine the exact cause of the light.

How do I permanently turn off my check engine light?

It’s important to note that the check engine light is a warning indicator, and turning it off permanently without addressing the underlying issue is not recommended. However, once the problem triggering the light has been resolved, the check engine light may turn off automatically after a certain number of drive cycles. Alternatively, a professional mechanic or dealership can use a diagnostic tool to clear the codes and turn off the check engine light.

What is a permanent check engine light?

A permanent check engine light refers to a situation where the check engine light remains illuminated continuously. It indicates that a fault has been detected in the vehicle’s system and requires attention. It is different from a temporary or intermittent check engine light that may come on and go off sporadically.

What is the difference between a check engine light and an engine light?

There is no significant difference between the terms “check engine light” and “engine light.” They both refer to the same warning indicator on the dashboard that illuminates when the vehicle’s computer system detects a potential issue with the engine or emissions system. The terminology may vary slightly depending on the manufacturer or model of the vehicle.

What is the most common problem when the check engine light comes on?

The check engine light can be triggered by a wide range of issues, and there is no single most common problem. Some of the common causes include a loose or faulty gas cap, oxygen sensor malfunction, catalytic converter issues, spark plug or ignition system problems, and various other sensor failures. It’s best to have the vehicle properly diagnosed by a professional to determine the specific cause of the check engine light.

What two steps should a driver take when a check engine light comes on?

When a check engine light comes on, here are two steps you should take as a driver:

Check the immediate condition of your vehicle:

Take a moment to assess the immediate condition of your car. If you notice any unusual noises, smells, or a significant change in performance, it’s advisable to pull over safely and turn off the engine. Continuing to drive with severe symptoms may cause further damage. However, if the car is running normally without any noticeable issues, you can proceed with the next step.

Schedule a professional inspection:

It’s crucial to have the vehicle inspected by a qualified mechanic or visit a dealership as soon as possible. They have the necessary diagnostic tools and expertise to identify the cause of the check engine light. Even if the car seems to be running fine, there could still be an underlying problem that needs attention. The mechanic will scan the vehicle’s computer for trouble codes and perform further diagnostics to pinpoint the issue accurately. They will then provide you with a diagnosis and recommended repairs or maintenance.


In conclusion, it can be annoying and perplexing for automobile owners to experience a situation when the check engine light is on but no codes are being shown. It means that although the vehicle’s onboard diagnostic (OBD) system has identified a problem, it is unable to provide specific fault codes to identify the cause of the issue.

This condition may occur for a number of causes, including intermittent defects, sensor problems, or problems with the OBD system itself. It is advised to seek the advice of a certified mechanic or make use of cutting-edge diagnostic equipment to perform a comprehensive inspection of the car and find any hidden problems. To avert potential harm and guarantee the vehicle’s peak performance, quick action is essential.

Remember that it’s crucial to address the check engine light as a preventative measure to keep your car reliable and healthy, even if there are no visible codes. That is all for this article, in which we talked about the reason why your check engine light is on but no code is visible. Also, we discussed if you should drive and how you can fix it.