Even if the illuminated check engine light causes worries, it at least warns you about the ongoing problems. But what if the check engine light itself is faulty and does not give any indication of problems occurring in the vehicle? That will be a pretty bad situation.
But why is the check engine light not working? The check engine light might not work due to the following reasons.
- The bulb is burnt
- The fuse is blown
- Faulty wiring
- Malfunctioning ECU
- Bad sensors
I will go over the detailed reasons and step-by-step solutions to help you fix this problem. Be with me till the end.
Table of Contents
Check Engine Light Not Working: Reasons and Solutions
Before talking about the solutions, I want to explain why the problems happen in the first place. Its reasons are given below.
1. The Check Engine Light Bulb Is Burnt
When the ECU detects a problem with any part of the engine, the check engine light comes up on the dashboard. Below the dashboard cover, there is a light bulb that illuminates the sign. As the vehicle ages, this bulb faces wear.
At some point, the bulb may get burnt. If the bulb is burnt, it won’t illuminate the check engine sign.
Step-By-Step Solution (3 Steps)
You need to replace the bulb to make the check engine light work again. Use a diagnostic scanner to read the error code. If the code is B1980, the check engine light bulb is faulty.
Step 1
Take the dashboard off. You should follow the user manual to find the right process for removing dashboards.
Step 2
Then, remove the instrument cluster from the vehicle. It will have multiple lights at the back to illuminate different signs. Remove the faulty bulb from the cluster.
Step 3
Take a new bulb that matches the specifications and install it. Then, assemble the instrument cluster and the dashboard. The check engine light should work fine now.
2. The Fuse Is Blown
Fuses are used in the electrical system of your car to protect different components from voltage surges. In such cases, the fuse gets blown and protects other components. If the fuse connected to the check engine light gets blown, the check engine light won’t work.
If there is no check engine light, but the car runs rough, there might be some issues with the fuse.
Step-By-Step Solution (4 Steps)
You should replace the blown fuse to fix the problem. After scanning the car, you will get the error code B1706 if the fuse is blown.
Step 1
Turn the car off and let it cool down. Then, pop the hood of your vehicle. Remove the negative cable from the battery terminal.
Step 2
Locate the fuse box in the engine bay. Check the user manual to find the box. Also, figure out which fuse is responsible for the check engine light. The fuse box should have a printed diagram under its cover.
Step 3
Remove the blown fuse and install a new fuse. The new fuse should match the amperage of the old fuse. Then, connect the negative cable to the battery terminal.
Step 4
Start the engine, and the check engine light should turn on.
3. Faulty Wiring
If electricity from the battery can’t flow to the check engine light bulb correctly, the bulb will not illuminate. It happens due to a faulty wiring.
Loose connections or damaged wiring can be the main reason for this problem. Sometimes, the check engine light flashes 11 times and then stops. This may indicate a problem with the engine misfiring.
Step-By-Step Solution (2 Steps)
Step 1
If the scanner shows the P0508, it indicates a wiring problem.
Step 2
You should hire an experienced mechanic who can identify the faulty wiring to the check engine light. Get the wiring repaired or replaced, as necessary. It might cost you about $100-200, including parts and labor.
4. ECU Is Malfunctioning
An ECU or electronic control unit collects signals from various sensors and processes the information. Then, it sends the necessary commands to different components.
If the ECU is malfunctioning, the check engine light won’t turn on even if the vehicle has problems.
Step-By-Step Solution (6 Steps)
Step 1
P0601 is the fault code for a malfunctioning ECU.
Step 2
You need to reset the ECU first. Turn the car off and open the hood.
Step 3
Remove the battery connections. First, take the negative cable off. It is the black cable on the battery terminal. Then, remove the positive cable as well.
Step 4
Now that the battery is disconnected, you need to press the horn several times. It will remove any charges remaining in the system.
Step 5
Connect the battery cables again. You should connect the positive or red cable first this time. Lastly, connect the negative cable.
Step 6
Turn the car on, and the ECU should be reset. If the problem persists, you may need to contact an expert to reprogram the ECU.
5. Faulty Sensors
The ECU depends on multiple sensors for data related to the engine performance. If any of these sensors are faulty or glitchy, they might not indicate any problem with the relevant component. So, the ECU won’t turn the check engine light on.
You may not be able to identify the problem until you use an OBDII scanner. These devices show the error codes that relate to various problems.
Step-By-Step Solution (3 Steps)
Step 1
Plug the scanner into the OBDII port of your car. I suggest using the BlueDriver OBDII scanner.
Step 2
Read the fault code on the scanner and match it with the list of codes on the user’s manual. You will find the faulty sensor by reading the code.
Step 3
Locate the faulty sensors and replace them. After replacing the sensors, the fault code should go away, and the check engine light should work normally.
Can I Perform a Check Engine Light Reset If It Is Not Working?
When the check engine light turns on, we tend to fix the issue behind it and reset the light. But if the light itself isn’t working, there might be no point in resetting the light.
If error codes indicate a faulty sensor, you must replace the sensor to make the light work again. Resetting or clearing the error codes won’t fix the light unless you solve the underlying reason.
People Also Ask
I answered some commonly asked questions about faulty check engine lights below. Check them out.
Can a check engine light correct itself?
Sometimes, the check engine light can reset itself after a few cycles of turning the car on and off. But if a blown fuse or burnt bulb is the reason, the check engine light will not correct itself.
Can I forcefully turn the check engine light on?
You can partially open the gas cap. It may cause the system to detect leaks in the evaporative emission control system and turn the check engine light on. But that won’t work when the bulb is bad, or the fuse is blown.
Conclusion
Not getting check engine lights at all is a similar problem to getting a check engine light. There are a handful of reasons behind the check engine light not working. I compiled all the reasons above so that you know what to check.
You also have the necessary steps for solving those problems. If you can diagnose the reason correctly and apply the respective solutions, the check engine light will turn on again. But don’t let it remain turned on unless there are problems with the car.
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