The check engine light, also known as the malfunction indicator light (MIL) or service engine soon light, is a common yet vital feature in modern vehicles. It alerts drivers to potential issues with the engine, transmission, or other systems, helping to prevent extensive damage and expensive repairs.
However, understanding why the light has turned on and how to address the problem can be confusing for many drivers.
In this comprehensive guide, we’ll cover everything you need to know about the check engine light, including its causes, diagnostics, and solutions.
Table of Contents
Overview of the Check Engine Light
The check engine light is an essential component of a vehicle’s on-board diagnostics (OBD) system. This system monitors various aspects of your car’s performance, such as the engine, transmission, and emission control systems.
When the OBD system detects a problem, it triggers the check engine light to alert the driver.
The check engine light can appear in two different ways:
- A solid yellow or amber light: This indicates a less urgent issue that should be addressed as soon as possible.
- A flashing light or red light: This signals a severe problem that requires immediate attention.
In either case, it’s crucial to have your vehicle checked by a professional mechanic to diagnose and fix the problem.
Common Causes of the Check Engine Light
There are numerous reasons why the check engine light might turn on, ranging from simple issues like a loose gas cap to more serious problems like a bad catalytic converter. In this section, we’ll discuss six of the most common causes.
1. Engine Problems
Various engine problems can trigger the check engine light. Most of these issues are related to poor fuel economy, such as:
- Extremely low oil pressure
- Driving at high speeds for extended periods or frequently towing heavy loads
- Engine misfires
2. Transmission Problems
The transmission is responsible for transferring the engine’s power to the drive wheels. Since it works closely with the engine, a transmission problem can negatively affect fuel efficiency and trigger the check engine light.
3. Faulty Emissions Equipment
Modern vehicles have numerous emissions control systems, such as the exhaust gas recirculation system, catalytic converter, and evaporative emissions system.
These components help reduce tailpipe emissions and improve fuel economy. However, issues like a loose gas cap or a faulty canister purge valve can cause the check engine light to turn on.
4. Ignition System Problems
The ignition system is responsible for igniting the air-fuel mixture inside the engine. Problems, like worn ignition coils or bad spark plug wires, can cause the check engine light to illuminate.
5. Faulty Modules and Sensors
The engine control unit (ECU) relies on various sensors to monitor and control the vehicle’s performance. Issues with these sensors, such as loose oxygen sensor wiring, a clogged mass airflow sensor, or a faulty oxygen sensor, can cause the check engine light to turn on.
If the engine coolant hasn’t been changed in a while, it can damage the engine thermostat and lead to overheating. In such cases, the check engine light will turn on, accompanied by a rising temperature gauge on the dashboard.
Read also >> Engine Emission Malfunction (Signs, Causes + More)
Read also >> Warning Light Malfunction (Here Is How To Fix)
Diagnosing the Check Engine Light
When the check engine light comes on, your vehicle’s computer stores a diagnostic trouble code (DTC) in its memory.
This code provides information about the detected issue. To diagnose the problem, a mechanic will connect an OBD-II scan tool to your vehicle to retrieve the error code.
Once the issue has been identified and resolved, the check engine light should automatically turn off. In some cases, you may need to reset the light manually using a diagnostic tool.
What to Do When the Check Engine Light Comes On
If the check engine light suddenly turns on while you’re driving, follow these tips:
- Remain calm and pay attention to how the car feels. Note any unusual noises or changes in performance.
- Drive slowly and head to the nearest service center or auto repair expert.
- If the check engine light is flashing or red, find a safe place to stop and turn off the engine. Schedule a check engine light service or call a mobile mechanic for assistance.
Typical Repairs for a Check Engine Light
Here are some common repairs and their costs for addressing a check engine light issue:
- Gas cap replacement: $18 t0 $22
- Oxygen sensor replacement: $60 to $300
Can you drive with engine malfunction light on?
It is not recommended to drive a hybrid vehicle with the IMA (Integrated Motor Assist) light on, as it could indicate a malfunction in the battery pack or other components of the IMA system.
Continuing to drive with the IMA light on can lead to risks such as the alternator not keeping the 12v battery charged up, which can eventually result in the car not starting.
Additionally, if the IMA light is on, it also lights up the CEL (Check Engine Light), and the car may not pass smog tests in some states, such as California.
Therefore, it is advisable to visit a certified dealership for proper diagnosis and repair of any issues related to the IMA system.
Is the engine malfunction light the same as the check engine light?
The engine malfunction light is typically the same as the check engine light. Both lights indicate that there is a problem with the engine or emissions system that requires attention.
If the engine malfunction light turns on, it could indicate a malfunction in the battery pack of a hybrid vehicle. It is important to visit a certified dealership for diagnosis and repair.
It is not recommended to continue driving the vehicle with the engine malfunction light on, as it could lead to potential risks such as the alternator not keeping the battery charged and the car not passing smog tests.
Is yellow engine light serious?
The yellow check engine light on a car’s dashboard typically indicates a less urgent issue that still requires attention. While it may not be an immediate emergency, it is important to visit a certified dealership or mechanic for diagnosis and repair.
Ignoring the light may lead to potential risks and expensive damage in the long run. Therefore, it is recommended not to continue driving with the light on and to get your vehicle diagnosed and repaired as soon as possible.
Causes of a yellow check engine light include engine problems, transmission problems, faulty emissions equipment, and ignition system problems.