what to do when check engine light comes on
Tips & Tricks

What To Do When Check Engine Light Comes On – 5 Solutions & FAQ

From what most automotive professionals advice about what to do when check engine light comes on, below are the main ones.

1) Check your dashboard Gauge

Do they show your car is experiencing low oil pressure or overheating? These indicators mean you should pull your vehicle over and shut off the engine immediately.

2) Tighten or replace your gas cap –

Usually gas caps these days have special seals as part of the vacuum fuel system. Probably a broken or misplaced rubber seal (on the gas cap) can cause the “check engine” light to come on.

3) Be aware of your engine’s performance –

If you notice your vehicle’s performance has been reduced, release your gas, also avoid towing or transporting heavy cargo.

4) Get an emission test –

It’s very possible your car will fail your state’s vehicle emissions test. Be sure to resolved all issues before the test.

5) Use a personal diagnostic scan tool –

A personal diagnostic scanner, if you know how to use one, will help you to be able to find what the problem is and may help you fix the minor ones.

What The Check Engine Symbol Looks Like



different check engine symbols and colors

The symbol is a car engine shape or outline & may be accompanied with the words “check engine” on the shape or beneath it. The color will vary depending on your car model as either orange, yellow, or red.

Onboard Diagnostics System (OBD) is like a lifeline to the car. It can detect the engine troubles much earlier than the symptoms are obvious. The computer system in your vehicle monitors the performance and regulates various things like the engine speed (RPM), the ignition timing, and fuel mixture. In some cases, it even controls the automatic transmission and tells it when to shift.

With so much technology packed under a single hood, various things can go wrong. Luckily, there is a built-in warning system within the vehicle to warn you before things get out of control. The ‘check engine’ light is a yellow indicator that turns itself on when the OBD detects a problem.

See how to get a free car diagnostic check engine light.

Why Does The ‘Check Engine’ Light Come On?

Whenever the OBD system detects a problem in the engine, it signals the driver by turning on the ‘Check Engine’ yellow light on the dashboard. The system also stores a related trouble code in its memory. These codes can help diagnose the problem and find a probable solution.

The ‘Check Engine’ light can come on due to various reasons. It can be trivial problems like a loose cap or a loose wire, or it could be something complicated like a misfiring engine or even a malfunctioning sensor. Only a diagnostic computer or maybe a scan tool can detect such problems.

What could cause the check engine light to come on – 10 Possible Reasons

There are many reasons for the Engine light being illuminated. Here are the top reasons:

  1. Oxygen Sensor Failure: The job of an oxygen sensor is to keep the ratio of fuel to air consistent. Excess fuel or oxygen in the engine prompts the sensor to equalize the issue using the car’s computer. However, these oxygen sensors fail occasionally mainly because you haven’t serviced the car or because you have used fuel that contains too much ethanol. Ignoring this problem will affect the mileage of the car and cost you a lot of money on fuel.
  2. Loose Gas Cap: This is a very common problem. The best solution is stopping the car and tightening the cap. However, if the cap is damaged, get it replaced at the next possible gas station. Driving around with a loose gas cap is dangerous for the people in the vehicle and for those around.
  3. Catalytic Converter Trouble: Catalytic Converters are the most expensive part to replace in a car. These converters are an important part of the exhaust system and help in converting toxic gases into harmless exhaust. A Catalytic Converter failure could be due to bad spark plus or even bad exhaust valves.
  4. Bad Ignition Coil: If the Catalytic Converter has failed, in all probability the ignition coil or your spark plugs in your car need to be changed too. The ignition coil converts low voltage electricity from your car’s battery and converts it into high voltage electricity. This sets the spark plugs in motion. The coils and plugs can both fail because of the high temperature they are exposed to.
  5. Bad Spark Plug Wires: When your car is in neutral and you hear the engine making sounds louder than you are used to, it means that your spark plug wires need replacing. These wires start eroding over time and the electricity generated to run the car becomes less consistent.
  6. Mass Air Flow Sensor Problem: The mass air flow sensor works in collaboration with your oxygen sensor and measures the humidity of the air and barometric pressure going into the combustion system of the engine. Adjusting to the weather conditions outside will become difficult for the car without the mass airflow sensor.
  7. Car Alarm System: Most car alarm systems develop problems over time. These alarm systems can drain the car’s battery or even prevent it from starting. Bad wiring or open connections can cause the alarm system to fail.
  8. Bad Vacuum Hose: The vacuum hose has one basic responsibility – Prevent Air Pollution. The car evaporates gas from time to time. This gas converts into toxic compounds when mixed with the air. The vacuum hose prevents the gas from turning into toxic fumes.
  9. Exhaust Gas Recirculation Valve: The Exhaust Gas Recirculation (EGS) system reduces the emission of nitrogen oxide from your car. This helps in improving the efficiency of your car as well. The EGS system prevents the hot exhaust fumes from leaving the car and redirects it back to the combustion chamber. This makes combustion easier due to the fuel staying warm.
  10. Dead Battery: With all the strain caused to the battery, it dies over time. Checking the alternator of the car is also a good option as more often it could be a problem with the alternator. However, if the battery is old, you are best advised to replace it.

How To Turn The Engine Light Off (Reset)

You can do many things once the engine light comes on. Before taking it to a mechanic, run certain checks to see if the problem can be fixed right away. First, try tightening the gas cap. This is a basic problem and you should see the light going off straight away. Still try reducing your speed or reducing some load off your vehicle.

If this does not help, I suggest keeping an engine diagnostic scanner like the Foxwell nt301. It reads the error code and inform you about the trouble. Most of the time the malfunction is the basic one and you can repair it yourself. If you prefer to see a Bluetooth professional scanner that is perfect for car owners.

If these basics steps don’t work, take your car to a professional to get it checked right away. If you ignore the light and continue to drive with the engine light on will cause more damage to the car than you can imagine.

What To Do When Check Engine Light Comes On Final Advice

One of the best ways to avoid the engine light coming on is to get your vehicle inspected every six months. You should always check for the following things when taking your car for servicing:

  • The battery condition and the charging system should be checked thoroughly.
  • Checking the battery cranking amperage and see if it meets the minimum requirements.
  • Checking the fan or the alternator belt as these are an integral part of your vehicle’s charging system.
  • Loose cable ends around your battery should be detected and rectified instantly.

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