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The check engine light flashing and car shaking can be caused by an engine misfire, defective ignition and fuel system components, or other issues. You can turn it off yourself in some cases and hire a mechanic to fix other problems.
This guide lists all the reasons and solutions for a flickering light.
JUMP TO TOPIC
- 1 Why Does the Check Engine Light Turn On and Car Shakes?
- 1.1 Check Engine Light Triggered by Engine Misfire
- 1.2 Issues in Various Ignition System Parts
- 1.3 Issues in the Car’s Fuel System
- 1.4 Faults in the Car’s Exhaust System
- 1.5 Faults in the Car VVT System
- 1.6 Various Air Intake Issues
- 1.7 Low Compression Issue in Cylinders
- 1.8 Issues in Various Valves
- 1.9 Faulty or Damaged Car Sensors
- 1.10 Worn or Injured Engine Mounts
- 1.11 Damaged or Faulty IAC Valve
- 1.12 Faults in the Car Charging System
- 1.13 Damage Due to Oil Replacement
- 1.14 Added Strain Due To Braking
- 2 How To Fix a Shaky Car With Glowing Check Engine Light?
Why Does the Check Engine Light Turn On and Car Shakes?
The check engine light turns on, and the car shakes because of a misfire in the engine. Damaged ignition system components, VVT systems, and sensors can also cause it. Moreover, the car’s fuel or charging system issues can lead to the check engine light blinking.
Check Engine Light Triggered by Engine Misfire
An engine misfire occurs when the air and fuel mixture fails to ignite correctly in one or more cylinders in the internal combustion engine. So they are unable to produce enough energy. It can result in the check engine light flashing, car slowed down, and much more.
Various issues can cause a misfire in the car engine. It may happen due to a flawed ignition system or fuel system component. A misfire caused by any of these issues can lead to a flashing light and, possibly, car shaking.
Issues in Various Ignition System Parts
Various issues in the ignition system of the vehicle can cause misfires. As a result, the engine light flashes. Here are some of the problems:
Faulty spark plugs cannot ignite the air-fuel mixture in the combustion chamber. Such bad spark plugs can lead to misfires.
Cracks or corrosion can damage the spark plug wires, disrupting the electrical signal needed for ignition and leading to engine misfires.
Ignition coils transform low voltage current from the car battery into high voltage signals to start ignition. Faulty ignition coils will not generate the high-voltage electrical spark and cause misfires.
Issues in the Car’s Fuel System
A fuel injector performs the function of spraying fuel in the combustion chamber at a specific time. Modern vehicles use injectors that directly inject highly pressurized fuel into the combustion chamber. This way, the fuel and air form a mixture in which they are both in equal ratios.
With time, injectors can become clogged with carbon deposits. In this case, they cannot inject atomized fuel when needed. A bad fuel injector can cause an uneven fuel mixture and lead to a misfire.
Fuel filters filter the contaminants and impurities from fuel before it reaches the engine. They can become blocked by debris or impurities in the fuel. The engine warning light can illuminate in case of a clogged fuel filter.
A fuel cap or gas cap covers the tank and acts as a seal. It would not allow the fuel to evaporate, thus preserving its quality.
A cracked or loose cap will cause the engine warning light to turn on due to fuel leakage. It will also cause low fuel pressure, leading to improper flow and injection of fuel in the engine’s cylinders.
Fuel pumps have the primary function of pumping fuel from the tank to the engine for mixing. It also maintains the pressure of fuel for proper engine operation. A faulty one will not be able to do so.
Inferior fuel or oil quality can affect combustion and engine performance. It might contain contaminants, low octane ratings, or additives. All these can cause knocking and misfires, leading to the engine light flickering.
Faults in the Car’s Exhaust System
A catalytic converter is an exhaust part detoxing harmful gases such as carbon monoxide. A faulty catalytic converter can cause a flashing check engine light and a shaky car.
Moreover, a faulty oxygen sensor will increase the car’s fuel consumption and emissions. The sensor will fail to measure the oxygen content in exhaust gases, leading to car shaking.
Faults in the Car VVT System
A Variable Valve Timing (VVT) system is primarily present in modern vehicles to optimize the opening and closing of engine valves. These include the vehicle’s intake and exhaust valves. It utilizes the following parts to achieve variable valve timing:
- Camshaft position sensor
- Crankshaft position sensor
- Camshaft phaser or adjuster
- Timing belt
- VVT solenoid
These components work together to optimize valve timings, resulting in better fuel economy and performance. A fault in the VVT system can cause the engine warning light to blink.
Various Air Intake Issues
Intake manifold gaskets are located between the manifold and cylinder heads in the combustion engine. They act as a seal between the two so the air-fuel mixture doesn’t disrupt. A faulty manifold gasket can cause vacuum leaks, leading to misfires.
The Mass Airflow (MAF) sensor measures the air mass entering the engine’s intake system. The engine control module (ECM) uses this information to inject the correct amount of fuel into the cylinders.
It can fail due to dirty filters or faulty installations. You won’t need to fix it urgently, but it will lead to poor fuel economy and misfires.
Low Compression Issue in Cylinders
When a piston rises, the mixture of air and fuel compresses. This produces a pressure that ensures proper ignition of the fuel. But if the compression or pressure is low in the cylinder, several issues occur, like bad ignition of fuel.
It will eventually lead to a misfire. Low compression in cylinders can be caused by:
- Damaged piston rings
- Faulty head gasket
- Faulty timing belt
- Worn pistons
- Valve issues
Issues in Various Valves
An Exhaust Gas Recirculation (EGR) valve recirculates the exhaust gas back into the burning chamber to reduce emissions. It also lowers the combustion temperature and NOx gases in the exhaust. It can frequently get stuck with carbon deposits.
This increases fuel consumption and causes poor engine performance. All these problems lead to a flickering engine warning light.
An Evaporative Emission Control System (EVAP) valve is a component of the emission control system of a vehicle. It stores fuel vapors from the fuel tank, prevents them from escaping into the atmosphere, and recycles them for combustion.
When the EVAP valve is stuck open, excess fuel vapors are stuck into the combustion chamber. This enriches the mixture of air and fuel and causes misfires.
Faulty or Damaged Car Sensors
Sensors are vital for the functioning of modern engines as they work in harmony to feed information to the vehicle’s computer. A defect in them can cause misfires in the engine. As a result, the check engine light comes on and car starts shaking.
These sensors are the parts of various systems crucial for the vehicle. Other than those already described, they include the Knock Sensor (KS) and Engine Coolant Temperature Sensor (CTS).
Worn or Injured Engine Mounts
Engine or motor mounts keep the engine in place by securing and supporting it. They reduce the engine movements and keep the engine’s noise and vibrations away from the rest of the vehicle by absorbing them. A broken engine mount can cause a shaking car, which will turn on the engine warning light.
This is because a shaky car can damage the vehicle’s components. They can turn the check engine light on and car shaking when stopped.
Damaged or Faulty IAC Valve
An idle air control valve (IAC valve) controls the airflow in the engine when the car is sitting still. It controls the amount of air that bypasses the closed throttle plate. As a result, the engine runs comfortably while the vehicle is not moving.
A damaged IAC valve can cause inconsistent airflow into the engine, leading to engine shaking. This will illuminate the warning light. Also, a check engine light flashing only at idle indicates that a significant misfire is taking place.
Faults in the Car Charging System
A car’s charging system charges the battery to provide electrical power to various parts, including the engine. One of its parts is an alternator that generates electrical power when the car runs. A defect in the charging system, especially the alternator, can lead to poor engine functioning, which will turn on the warning light.
Damage Due to Oil Replacement
Changing oil does not directly cause the warning light to turn on. However, some issues might occur while doing so, like accidental damage to components or ECM reset. Sensors can also be damaged during the process, causing car shaking and check engine light on after oil change.
Added Strain Due To Braking
When you apply brakes, the engine works harder because of the additional load. If a misfire is also occurring at this time, it will become much more substantial. This causes the check engine light on and car shakes when braking.
How To Fix a Shaky Car With Glowing Check Engine Light?
To fix a shaky car with glowing check engine lights, you can find the trouble codes to solve a particular problem. You should replace faulty components, like spark plugs, ensure normal fuel pressure, and fix damaged sensors. In case of inexperience or extensive damage, consult a mechanic.
Find Trouble Codes With an OBD Reader
An OBD reader is a device that gets information about the vehicle from its On-Board Diagnostics (OBD) system. It is plugged into the vehicle’s OBD port, which is present in most modern cars. You can buy it from an auto parts store or use it online.
These are the steps to use it:
- Locate the OBD port. It is a trapezoid, usually located under the dashboard near the driver’s seat.
- Turn off the vehicle’s ignition system before plugging the reader.
- Insert the OBD reader’s connector into the port and gently push it in.
- Depending on the reader, the information may be displayed on the reader or a smartphone app if your reader is connected to it via Wi-Fi or Bluetooth.
- Now, you will have the diagnostic trouble codes and other relevant information.
- Once you’re done, turn off the ignition and disconnect the OBD reader.
- You can then search the code you got online to find the issue. The OBD website can help you find the meaning of the code.
- Once the issue is solved, the flashing check engine light then stops.
The code can be stored in the ECM memory until manually removed. Once you have fixed the damaged parts, connect the OBD reader again and press and hold the erase button.
The screen will then change. Press that button again for confirmation, and the code will be erased.
Inspect the Various Car Sensors
You can visually inspect the sensors or use diagnostic tools. You can perform the functioning tests to find out the faulty sensors. Contamination or dust accumulation is a common reason for sensor malfunction, especially the MAF sensor.
Cleaning them may solve the issue. You can hire a professional mechanic to fix the bad engine sensors if you are inexperienced.
Maintain a Normal Pressure of Fuel
You can use a unique gauge or advanced scanners to determine the fuel pressure. If it is much lower than usual, you must diagnose the faulty vehicle or engine components and fix or replace them.
Fix or Replace the Damaged Car Part
If the codes inform you about a damaged component like a bad spark plug, lousy spark coils, faulty fuel injectors, damaged catalytic converter, or any other part, you should try to fix them. Similarly, it would be best if you rectified a bad IAC valve. Depending on the damage, you can repair or replace these components.
Take the Car to a Mechanic or Repair Shop
Pay attention to a flashing engine check light. These warning lights indicate something concerning and significant, like a misfire.
If you have used all the above methods and it doesn’t go off, consult a professional mechanic or visit an auto shop. They have the tools and expertise to solve such issues. The cost of fixing or replacing the components depends on the damage and the part.
If you are wondering: “If I have the engine light on and car shaking, can I drive?” the answer is that it might be okay to do so if you have a solid check engine light, but if you have a flashing one, you must not continue driving.
This type of light blinking must always be addressed. If you continue to drive in this condition, irreversible damage to your vehicle can be caused.
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