Why is My Check Engine Light Flashing?

The check engine light activates to draw the driver’s attention to possible vehicle engine problems. If you see this check engine light flashing, it signifies a severe issue that requires immediate attention. Whereas a steady check engine light is less urgent, indicating a need to have the car inspected.

Sadly, the check engine warning light offers little in terms of diagnosis. It’s definitely engine related, often triggered by emissions, but could be also caused by a broad range of components failing.

Yet the last thing you should do is simply ignore it. While you may not suffer immediately, an inconvenient and costly breakdown may be on the horizon.

What to Do If Check Engine Light is On

You should take prompt action to diagnose and fix your engine problem. This may involve a costly trip to the local garage, or if you’re handy with a spanner, painfully diagnosing the problem yourself.

Alternatively, you could get your hands on an OBDII scanner and plug directly into your vehicle’s onboard computer. This enables you to read specific error codes and pinpoint the source of the problem.

The check engine light is often triggered by emissions, due to problems with ignition and exhaust systems. Here are the most common causes to help you diagnose the problem yourself.

10 Common Causes of Check Engine Warning Light

1. Loose Fuel Cap

Sometimes it can be this simple! If your fuel cap is not properly fastened, your gas may slowly leak or evaporate out. This is certainly going to decrease your fuel economy. Your vehicle’s check engine light may be triggered by this directly or even as a result of relating problems.

2. Spark Plugs

Spark plugs are responsible for igniting the compressed fuel and producing power within an internal combustion engine. Spark plugs are not expensive or difficult to replace, yet a faulty one will severely affect the economy and performance of your car.

If they are underperforming, they often cause check engine light flashing. When left in this state, it can damage more costly components such as the catalytic converter.

3. Ignition Leads

These leads carry the electrical charge to the spark plugs, enabling a strong enough spark to ignite the fuel. If old or damaged leads cannot carry enough electrical current to spark plugs, their performance is hindered.

The negative impact is the same as with spark plugs, reduced fuel economy, and overall engine performance.

4.  Coil Packs

Another ignition related component, vital for providing the enough electrical charge to the spark plugs.

They can often degrade with age, especially if subjected to extreme temperatures. If damaged coil packs are left unchecked, it can soon result in further engine woes.

5. Oxygen Sensor

The oxygen sensor ensures the correct mixture of fuel and air are being fed to your engine. It measures both the unburnt oxygen in the exhaust system and even measures the amount of fuel remaining in the tank.

A faulty oxygen sensor is going to provide incorrect readings to the vehicle’s computer. It’s likely to flag your check engine light and greatly reduce your gas mileage.

6. Mass Air Flow Sensor

Another vital engine sensor, this one controls the inlet of air to the engine. Readings by the vehicle computer to accurately calculate the fuel and air mixture.

If this sensor is defective, engine combustion can be affected significantly. It can lead to backfires, sluggish performance, and reduced economy.

7. Fuel Injectors

Fuel injectors can be one of the most difficult components to accurately diagnose. Their failure is usually a gradual process, as they become clogged and inefficient.

Low-quality fuel and debris within the fuel tank can damage injectors, eventually causing them to fail.

8. Exhaust Gas Recirculation Valve

Named EGR for short, this value helps the vehicle control engine emissions and efficiency. If this value is faulty, it’s likely you will experience engine misfires, reduce performance and economy.

You’ll certainly want to fix this quickly, before causing further engine damage.

9. Thermostat

The vehicle’s thermostat manages the engine’s operating temperature by adjusting the flow of coolant. If this device fails your car may be liable to overheat, possibly even blowing the head gasket.

Thermostats can suffer from corrosion due to extreme temperatures, acidic environments or incorrect mixtures.

10. Catalytic Converter

Catalytic converters are notoriously expensive, they can be up to $2000 to replace! They help reduce emissions as exhaust gasses pass through precious metals such as platinum.

Not only will this problem plague you with a check engine light, it will affect gas mileage and even fail an emissions test.


Whether you notice your check engine light flashing or steady, make sure you deal with the problem as soon as you can.

You could make your life a whole lot easier by plugging an OBD2 scanner. Check out our best OBD2 scanner reviews and get the best bang for your buck!

How to Easily Check Your Car is OBD II Compliant

Thinking of buying an OBD II scanner to check up on vehicle health? Well, first you better be certain your car is OBD II compatible. Also, you don’t want to make the common mistake of getting muddled up with the older OBD I.

Thankfully, there are a number of very easy ways to identify OBD II compliant cars. Once you have familiarized yourself with these, you can buy the best OBD II scanner with great confidence.

Quick Reminder: What Exactly is OBD II?

OBD stands for on-board diagnostics. It’s a standard computer-based system built into all cars manufactured since 1996, even light-duty vehicles and trucks.

The OBD monitors the performance of the engines’ major components including emission. This crucial system will flag errors and even send a warning to drivers through dashboard check engine lights, otherwise known as a malfunction indicator light.

When a user or mechanic plugs in a handy OBD II scanner, they gain access to extensive fault codes that can be used to self-diagnose vehicle problems. It can be used to gain a great insight into your car’s health, thus avoiding costly failures or repair bills in the future.

3 Simple Ways to Check Your Car is OBD II Compliant

1. OBDII Compliance By Year of Manufacture

Due to conformity with the legal requirements, all vehicles manufactured in the US since 1996 (and many late 1995 models) have OBD II systems by law.

European and Asian manufactured vehicles also had to follow suit, all gasoline vehicles were OBD II compliant since 2001. Diesel vehicles were also included by 2004. Australia and New Zealand received the same regulations for all vehicles from 2006.

Some vehicles manufactured before these dates still have ODB II, otherwise, they have the older OBD I system. These will require an older type scan tool and do not provide as much diagnostic information.

If your vehicle was not manufactured before the legal requirements, use these next methods for further verification.

2. Search For the OBD II Compliant Name Plate

To absolutely confirm your vehicle has an OBD II system, look for the sticker/nameplate that details emission control information. In almost all cases it will be located under the hood, yet its exact location varies greatly between models.

Look for the words, “OBD II Certified” or “OBD II compliant”.

3. Confirm OBD II Compatibility By Finding the Connector

Older, OBD I systems are not easily seen or accessible to drivers. Usually, the connector is buried deep within the vehicle’s dashboard.

Fortunately, OBD II systems are far easier to locate and plug into with a scan tool. OBD II connectors are typically located under the driver’s seat, ashtray area, driver’s foot well or occasionally, in the boot area. This is a great advantage when it comes to installing an OBD II scanner in an accessible area.

Otherwise, you may choose to purchase a Bluetooth OBD II scanner. Then by plugging the Bluetooth OBD II module onto the connector you will gain wireless access to the system. This is an ideal option for those who only wish to use on a single vehicle at one time.

The exact location will vary greatly depending on your vehicle make and model. If you don’t want to hunt for yourself, consult a friendly mechanic or the vehicle handbook.


Before you buy an OBD II scan tool, you need to be 100% certain your car is OBD II compliant.

Check whether it was manufactured since 1996 and use the additional methods to confirm OBD II compliance. Finally, you don’t want to miss our best OBD II scanner reviews!

How to Reset Check Engine Light Using 2 Easy Methods

reset-check-engine-lightWhen the check engine light starts rears its ugly head, it’s crucial you act upon this distress signal. However, even once you’ve diagnosed the cause and rectified the problem, the check engine light often remains. Even more annoyingly, turning off the check engine light is not as simple as you would like.

Usually, we are forced to return the vehicle to a garage or manufacturer to extinguish it. However, there are two basic methods for resetting a check engine light. If you already own an OBD2 scanner, you can easily read and clear error codes. Or if you are without, you can try disconnecting the battery, erasing the error data.

It’s worth knowing that using an OBD2 scanner is a greatly preferred method. It’s easier, more reliable and the same method used by vehicle manufacturer’s and professional mechanics- often at great cost to the customer!

Also, disconnecting the battery is not always guaranteed to remove all the error codes. To help you make an informed decision and finally turn off check engine light, we’ve explored both methods in greater detail:

How to Reset Check Engine Light By Disconnecting Your Battery

Reset Check Engine Light

Only attempt this method if you are relatively confident with DIY vehicle repairs. Disconnecting the battery from the car will require a small selection of tools and basic electrical safety knowledge.

Once you disconnect the battery terminals, you will still need to run down the remaining electrical charge in the system. This can be achieved by running the lights and finally using the horn.

Once the electric charge has been disputed, the ECU should lose the troubles codes stored in the temporary memory. This will often turn off the engine check light on older vehicles. However, it’s less likely to work with newer cars, plus it may lead to the undesirable loss of numerous settings.

Also, be aware that prolonged horn can overheat the circuits. Make sure you allow for periodic breaks.

For these reasons, this is not a recommended method for newer vehicles.

How to Turn Off Check Engine Light With an OBD2 Scanner

How to Turn Off Check Engine Light

Using an OBD2 scanner is by far the safest and easier option, as long as your vehicle is OBD2 compliant. You don’t even need to be an experienced mechanic to use one!

They offer a whole host of additional features for diagnosing vehicle health. They are easily affordable and could even save you $1000s in the long run!

First, you must connect a trusted OBD2 scanner to the vehicle’s OBD2 connector port. You can find the OBD2 close to the steering column on the bottom side of the dash panel.

Turn the key to ignition and select the read codes function to run a full diagnostic scan. This should provide instantaneous identification of error codes. Depending on the functionality of your device, it may even provide potential causes.

Once you have made a note of trouble codes and addressed the problems, press the erase code button to reset the check engine light. Finally, you should take your vehicle for a test drive before re-diagnosing the system.

If the fault codes do not return, it signifies you have fixed the problem. If it does return, problems still remain! You’ll need to investigate further or relay the details to a professional mechanic.

This is a general procedure, but exact guidance will be provided by your model specific instructions. Make sure you do your research before purchasing, they come in a range of prices and functionality. Check out our best OBD2 scanners reviews for guidance!

Oxygen Sensor Replacement

Quite often, a home mechanic removes a brand new oxygen sensor from the box and improperly installs it. This mistake ruins it, or at least shortens its life. When replacing the oxygen sensor, here are some tips to gain the most life possible from it:

  • Always use an oxygen sensor wrench or socket when removing and installing the sensor. These tools are designedto apply even torque to the sensor. Under no circumstances should an adjustable wrench be used on an oxygen sensor.
  •  In order to facilitate easy removal of a sensor at a later time, apply anti seize compound to the threads prior to installation. Take care to only apply a small dab to the threads, and don’t get any compound on the tip of the sensor.
  •  The wires in the sensor are delicate and can be broken or pinched. Install the oxygen sensor prior to connecting the wires to the harness. Also take care when routing the wires. Exhaust systems are extremely hot and can quickly melt oxygen sensor wires.
  •  Oxygen sensors typically come with a plastic cover over the tip. Keep this cover on the sensor until you are ready to thread it into the exhaust system. This helps prevent contaminants from entering the sensor.
  •  Remember that oxygen sensors operate at 600 degrees F or more. Even if the vehicle is not running, if the ignition is on, the sensor’s heaters will most likely be engaged and heating the sensor. Prior to removing the sensor, turn off the engine and let it cool for an adequate amount of time.
  •  When changing exhaust systems or exhaust pipes, keep in mind that the pipes are often coated with light oil when being bent. This oil is usually not cleaned off prior to installation, burns off and can harm an oxygen sensor. If the exhaust components prior to the oxygen sensor are replaced, run the engine with the exhaust sensor removed for 10 minutes to burn off the excess manufacturing oil.

So what Causes Oxygen Sensor Failure?

Oxygen sensors operate in a demanding environment and therefore are pretty tough sensors. But, as previously stated, they are considered a consumable sensor that eventually wears out and requires replacement. There are several factors that can accelerate their replacement schedule. These factors include:

  • Running the incorrect fuel type in the vehicle. Leaded gasoline, such as leaded race gas, shortens the life of an oxygen sensor to as short as a matter of hours. A sensor that has been running in leaded gasoline typically has a rusty color on the tip of the sensor.
  •  Engine oil ruins a sensor quickly by fouling the tip of the sensor, so that it can no longer sample the incoming exhaust stream. If an engine is burning oil through a mechanical issue or a PCV problem, the oxygen sensor’s performance degrades rapidly.
  •  Excessive grease, dirt, or other contaminants built up on the outside of the sensor wires reduces or eliminates the capability for the sensor to draw in outside oxygen for sampling. Sometimes the wires can be cleaned but, due to the miniscule size of the passages, they are difficult to get completely free of contaminants.
  •  If engine repairs are made and sealants are used, the sealants must be labeled as “sensor friendly.” Many sealants contain chemicals, which will foul or damage the sensor if the chemicals can reach the exhaust stream.
  •  If a head gasket or intake gasket is leaking and antifreeze is being burned in the combustion, the byproduct of the burned antifreeze is poisonous to the oxygen sensor and ruins it quickly.
  • Overly rich conditions can foul the tip of the oxygen sensor with black soot,  rendering the heater circuit or the sensor itself useless. Occasionally, the tip can be burned clean with a propane torch, but usually, the sensor has to be replaced.