Prius Check Engine Light Reset (Expert Guide)

Vehicles give different signals to indicate when something is not right. A lot of faults in vehicles can be identified through the ticking and clicking sound the engine produces or by clear physical damages.

However, a very simple way to identify hidden or complicated faults is to observe if the “check engine light” has come on. The check engine light needs a reset to pass the vehicle emission test, and it is better to have the lights off. In a lot of instances, the check engine light is triggered for a reason and will not come on; there’s nothing wrong.

However, the check engine light may remain on and not go off, notwithstanding the fact that one might have tried to let it go off by fixing the problem that triggered it in the first instance.

Most times, this usually occurs when the vehicle’s computer system has not reset itself. It could be that the issue had just been fixed, and one expects that the light ought to go off immediately after the vehicle is fixed. However, this is not always the case.

Regardless of one’s perspective, if the check engine light starts flashing, never ignore this signal. Although, it is possible to turn it off. In some cases, nothing is wrong with the vehicle, even if it’s on. This is one interesting thing about vehicles, and one may never understand what is going on until one knows what to look out for.

The major thing here is to know what the real problem is. That can be done using OBD2 scanners to detect what the issue is.

After going through the explanations above, if one still prefers to reset a vehicle’s check engine light, which is possible, the steps involved in resetting the light will be discussed in this write-up.

However, before proceeding, make sure of any possible problem that could trigger the check engine light. From the above statement, we will look at the possible factors that can trigger the check engine indicator.

How to Reset the Check Engine Light on a Toyota Prius

Prius Check Engine Light Reset

The Odometer Technique

Follow the procedure below to properly reset the engine light using and solve vehicle problems and complications using this technique:

  1. Switch off the engine while the key fob remains in the ignition.
  2. Push down the brakes while pressing the power button to start the vehicle. Keep pushing down on the brakes, as the odometer trip button is pressed.
  3. Switch off the vehicle while the brakes and ODO button is being held down. After doing this, turn the vehicle on while the ODO and brake are still held down.

The odd meter shown on the dashboard turns into lines made of dashes, and a time count starts.

When these dashes reach the right, the odometer starts flashing 000000. Then, It will switch on again, but the check engine light would have gone off this time.

To Reset Check Engine Light With A Code Reader

Find th vehicle’s onboard diagnostic link, usually underneath the vehicle’s steering. Then plug in the code reader.

Start the ignition; afterward, the red button on the code reader should be pressed.

A number of errors will be displayed; take note of these codes, and ensure they are kept safe. The codes can be interpreted through the vehicle owner’s manual.

Immediately the trouble codes are interpreted and understood, the problem becomes clear and obvious.

One may choose to fix any issue detected without help or take the vehicle to a professional mechanic (for a faster solution and to save time, not forgetting that the codes become extra knowledge for the mechanic as well). Replace faulty components when necessary.

Once this is done, press the erase or clear button on the code reader to remove error codes.

After solving this issue, please switch off the ignition before switching it on again. Then observe if the check engine light has gone off or is still displayed.

Also, re-check with the scanner to confirm if the initial error codes it gave will pop up again or not. Always switch off all other vehicle accessories, such as the radio when using this method. Error codes are a set of letters and numbers, and to see error codes on the scanner, press the “read” on the code reader.

After the erase button has been pressed on the scanner to clear the error code, the check engine light should turn off without delay. It is also advisable to take note of the codes as they lead to what is actually wrong with the vehicle, making it easy to repair the vehicle accordingly.

Disconnect The Car Battery

Disconnecting the vehicle’s battery is another way to reset the engine light. This technique is also called the ECM Hard Test Technique. Go through the steps below to know how easily a vehicle’s battery can be disconnected and reconnected. Otherwise, meet a professional for assistance.

Lift the vehicle’s hood and find the battery. Take out the two cables connecting the battery (negative and positive) at its battery terminals. Press the horn or switch on the vehicle light for about 30 seconds.

By doing this, the electricity left in the vehicle’s capacitor is drained. Both can be done for a faster result. Wait for 15 minutes, then reconnect the positive and negative cables to the appropriate terminals.

This method will clear every error code and reset other electronic components of the vehicle. If the check engine light does not go off after this, the best thing to do is to seek assistance from a professional.

Turn the Ignition On And Off

This technique involves putting the key into the keyhole and turning the ignition on and off about three times, with a second interval in between. After this, drive the vehicle to confirm if the light has gone off.

The vehicle may also self-reset if the issue is only minor. Then, the vehicle’s computer setup will check the problem again and fix it.

Restarting The Fuse Of The Car

This does not apply to new vehicles; one may choose to remove the engine control unit‘s (ECU) fuse in the vehicle’s fuse box. Doing this will cause a break between ECU and the engine light connection. Return the fuse to its normal position then confirm if the light goes off or not.

Get Mechanical Help

At times, the check engine light may occur at frequent intervals and appear again within some weeks or even days, which could indicate a severe problem.

If this continues after going through all the resetting techniques provided above, the next thing to do is to drive to a repair store so that professionals can handle it.

What Causes Engine Check Light On?

Before fixing an issue, one must realize the cause or source of such an issue. This principle also applies to vehicles. As stated earlier, the check engine light notifies the vehicle driver that there is a mechanical or electrical fault with the vehicle.

In certain instances, a mistake from the vehicle’s engine can cause this also. Therefore, before checking other parts of the vehicle, make sure the engine has no visible slip-ups.

If the engine looks fine, one can proceed to check other vehicle components. Possible factors that can trigger the check engine light include:

1. Faulty Oxygen Sensor

The vehicle’s oxygen sensor aids in the burning up of gas in the engine. This engine component calculates the quantity of unburnt oxygen found in the exhaust. The vehicle starts to burn extra fuel when the oxygen sensor becomes faulty. If fuel burns excessively, it will result in damage to the vehicle’s catalytic converter and spark plugs.

As far as the oxygen sensor is not working as expected, the check engine light will come on. It may become necessary to consult a professional mechanic to help replace the sensor. If not, one will be unable to pass the vehicle’s emission test.

2. Faulty Catalytic Converter

Another factor that can cause problems for a catalytic converter aside from having a damaged 02 sensor is poor maintenance of the vehicle.

Acts like irregular oil removal and driving short distances can have an effect on the catalytic converter. Having a clogged catalytic converter could be the consequence that will trigger the check engine light.

Also Read: 7 Bad Rear Differential Symptoms (And How to Fix)

3. Vacuum Leakage

One duty of a vacuum system in a vehicle is to lessen toxic emissions. Therefore, if the vacuum starts to leak, the vehicle will settle or spurt at a rare high PRM. This leak is most times caused by dry vacuum hoses, loose connections, or damaged fittings.

4. Loosed Gas Cap

Suppose a loose gas cap could occur due to the driver’s mistake or negligence. When this happens, the fuel delivery system is disrupted because the vehicle fails to maintain the necessary pressure required to move fuel around.

This will lead to loss of fuel, and the check engine light will come on as a consequence. It could be that one did not put the gas cap back in its position or failed to tighten it as required after fueling. Anyone may be caught up in this situation, particularly in a hurry. But It is advisable to treat the gas cap with caution.

This is because gasoline is highly flammable, so it is important to drive a vehicle with its gas cap in the proper position. A lot of times, if the check engine light comes on due to a gas cap-related problem, it should go off once the cap is properly tightened the cap.

For this reason, make sure the gas cap is returned to its position and tightened to satisfaction after fueling the vehicle. A faulty gas cap should be replaced as soon as possible.

5. Mass

This component regulates the amount of air finding its way into a vehicle and helps the vehicle in adjusting to elevation-related changes. If this component becomes faulty, one may experience sudden changes in the throttle pedal, tough idling, and reduced gas mileage.

6. Faulty Thermostat

A thermostat regulates coolant flow in an engine. It will trigger the check engine light displayed on the dash if it becomes faulty.

7. Defective Alarm Systems

Vehicle alarms are designed to work against theft. However, if the alarm system does not work as it should, it causes the check engine light to come on. Not every alarm works effectively, so make sure a good and effective one is gotten.

Do not patronize cheap alarms because if the alarm starts to malfunction, it can cause the check engine light to come on or cause problems for other components of the vehicle.

8. Faulty Ignition Coil And Spark Plugs

The ignition coil supplies power to the spark plugs of a vehicle, which causes them to produce sparks. The spark then burns the air and fuel mixture in the vehicle’s cylinder.

When the ignition coil gets faulty, spark plugs are unable to get the adequate electricity required to perform their function. Hence, it will trigger the check engine light.

In certain instances, the coil may be in good condition while the plugs are worn or old; this will cause the engine to misfire and consequently trigger the check engine light. So, make sure damaged ignition coils and worn-out or old spark plugs are replaced without delay.

8. Dead Battery

A vehicle’s battery should remain in good condition for about 5 – 7 years. Upon expiry, it can develop charging problems which can trigger the check engine light. Also, depending on the level of usage, it may wear out before the time span stated above. So, if a battery does not charge while causing other problems, it may become necessary to replace it.

Also Read: Effects And Symptoms Of Too Much Transmission Fluid (+ Solutions)

Frequently Asked Questions – Prius Check Engine Light Reset

Can I reset the check engine light myself?

Using the on-off technique is a good way to fix the engine check light in a vehicle. It is a technique that forces the vehicle’s computer system to refresh all stored data by rebooting by placing the key in the keyhole and turning it on for a second or two, and turning it off for a similar time span. Go through this step about three to four times.

What do I do if my Prius check engine light is on?

If a Toyota Prius 2020 starts showing the check engine light, the problem requires immediate attention, and a professional mechanic should check the vehicle without delay. A warning light is a severe problem; if left unattended, it will cause more severe problems to the vehicle.

How do you reset the check engine light on a 2011 Toyota Prius?

There are different methods of resetting the engine light in a vehicle; one is by repeatedly turning the ignition on and off a few times. Also, it can be done by disconnecting the battery and reconnecting it. Another way to fix this is to get an OBD2 scanner (they are very cheap and affordable) and adhere to the directives provided.

Can You Reset Check Engine Light Without Disconnecting The Battery?

A lot of techniques can be used to reset the check engine light. So, it is possible to reset the warning light without touching the battery. A code scanner can be used instead of disconnecting the battery. In certain instances, the check engine light will go off on its own by driving the vehicle for some time. However, never forget to fix whatever problem the vehicle has.

How do you reset the check engine light on a Toyota without a scanner?

To reset the check engine light on Toyota vehicles without using a code scanner, remove the cable attached to the battery’s negative terminal and wait for some minutes. This should reset the vehicle’s diagnostic system. Once the reset is done, all underlying issues should be resolved, which will make the check engine light go off.

How many miles do you have to drive to reset the engine light?

This is something a lot of drivers are likely not to know. After erasing the vehicle’s computer system, the vehicle should cover another 50 – 100 miles before one starts thinking of resetting. As one drives the vehicle, its computer monitors every sensor and vehicle and records the results.

How do you get the check engine light off in your car?

Switch off the engine, find safety gloves and glasses, and locate the battery’s negative terminal. With a wrench, the nut attached to the negative terminal should be loosened, then detach the negative cable connected to the battery. After the above procedure, fix the negative cable back in its place before using the wrench to tighten it properly.

How Do I Permanently Delete Engine Codes?

A code reader or an OBDII scanner is required to erase engine codes permanently. This procedure was discussed earlier, and to save time, it would be nice to look up the earlier discussion about the procedure. Remember, Never clear error codes if uncertain as regards facts like the origin of the error code, its meaning, and so on. Endeavor to fix these problems, too, before clearing the trouble codes.

Final Thoughts

At this point, one must have learned the various techniques to reset the check engine light. One such technique is to use an which is the use of an OBD II scanner or a code reader. This method will not only reset the check engine light but also identify what the issue is.

For other techniques, remember that different faults in a vehicle can trigger the check engine light. So it is best to start with finding out the actual problem before fixing it and resetting the check engine light. If the check engine light is left without resetting it, one can not pass the vehicle’s emission test.

This article tried to go through every step and procedure in a simple way. All the directives above are not so difficult and can be done without the help of an expert. Nonetheless, things could go south. If one is still unable to find a solution to the problem after carrying out every step, seeking assistance from a professional mechanic is non-negotiable at this point.

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