The dreaded check engine light. It’s a symbol that strikes fear into the hearts of many car owners. Seeing it illuminate on your 2019 Toyota Highlander’s dashboard can be unsettling, prompting thoughts of expensive repairs and inconvenient breakdowns. But before you rush off to your mechanic, it’s worth understanding what the light signifies and whether you can address the issue yourself. This comprehensive guide will walk you through the process of resetting the check engine light on your 2019 Toyota Highlander, explore the potential causes, and outline important considerations to keep you safe and informed.
Understanding the Check Engine Light
The check engine light, often referred to as the malfunction indicator lamp (MIL), is a crucial component of your Highlander’s onboard diagnostic system (OBD II). Its primary function is to alert you to potential problems within the vehicle’s engine, emissions control system, transmission, or other critical components. When the system detects an anomaly, it illuminates the light on your dashboard.
The check engine light doesn’t always indicate a catastrophic problem. It could be triggered by something as minor as a loose gas cap or a more serious issue like a faulty catalytic converter. The key is to understand that the light is a warning signal, prompting you to investigate the underlying cause.
Interpreting the Light: Solid vs. Flashing
The behavior of the check engine light offers valuable clues.
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A solid, consistently illuminated light typically indicates a problem that requires attention but isn’t necessarily an emergency. You should schedule a diagnostic check as soon as possible, but it’s generally safe to continue driving for a limited time.
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A flashing check engine light is a more serious warning. This usually signifies a severe engine misfire, which can damage the catalytic converter. If you see a flashing check engine light, you should pull over to a safe location as soon as possible and avoid driving the vehicle until the problem is diagnosed and resolved. Continuing to drive with a flashing light can lead to more extensive and costly repairs.
Accessing the Diagnostic Trouble Codes (DTCs)
The check engine light is triggered by Diagnostic Trouble Codes (DTCs). These codes are stored in the vehicle’s computer and provide information about the nature of the problem. To access these codes, you’ll need an OBD II scanner.
OBD II scanners are readily available for purchase online or at auto parts stores. They range in price from relatively inexpensive basic models to more advanced versions with additional features. Many auto parts stores will also perform a scan for free as a service to customers.
Once you have an OBD II scanner, plug it into the OBD II port located under the dashboard on the driver’s side of your Highlander. Turn the ignition key to the “on” position (without starting the engine) and follow the scanner’s instructions to retrieve the DTCs.
Each DTC is a five-character code that identifies a specific problem area. For example, a code like “P0420” indicates a problem with the catalytic converter. Once you have the codes, you can research them online or consult a repair manual to understand the potential causes and solutions.
Methods for Resetting the Check Engine Light
There are several methods you can use to reset the check engine light on your 2019 Toyota Highlander. It’s crucial to remember that resetting the light doesn’t fix the underlying problem; it only clears the code and turns off the light. If the issue persists, the light will likely reappear.
Using an OBD II Scanner
The most reliable and recommended method for resetting the check engine light is using an OBD II scanner. After retrieving the DTCs and addressing the underlying issue (if possible), you can use the scanner to clear the codes and reset the light.
- Plug the OBD II scanner into the OBD II port.
- Turn the ignition key to the “on” position (without starting the engine).
- Follow the scanner’s instructions to clear the codes. The specific steps may vary depending on the scanner model, but typically involve selecting an option like “Clear Codes,” “Reset Codes,” or “Erase Codes.”
- Turn off the ignition and unplug the scanner.
- Start the engine to see if the check engine light remains off.
If the light reappears, it indicates that the underlying problem has not been resolved.
Disconnecting the Battery
Disconnecting the car battery is an older, less precise method that can sometimes reset the check engine light. However, it also resets other electronic systems in your Highlander, such as the radio presets and the engine control unit (ECU) memory. This means the ECU will have to relearn certain parameters, which can affect engine performance temporarily.
- Ensure the engine is off and the ignition key is removed.
- Locate the negative terminal of the battery (usually marked with a “-” sign).
- Loosen the nut on the negative terminal clamp.
- Carefully disconnect the negative terminal clamp from the battery post.
- Wait for approximately 15-20 minutes. This allows the vehicle’s computer to fully discharge and reset.
- Reconnect the negative terminal clamp to the battery post and tighten the nut securely.
- Start the engine to see if the check engine light remains off.
Important safety precautions: Always wear safety glasses and gloves when working with a car battery. Be careful not to touch the positive terminal with your wrench while disconnecting the negative terminal, as this can cause a short circuit. Also, be aware that disconnecting the battery will reset your radio presets and other electronic settings.
The “Gas Cap” Method
Sometimes, a loose or faulty gas cap can trigger the check engine light. This is because the gas cap is essential for maintaining pressure within the fuel system. A loose gas cap can allow fuel vapors to escape, triggering an evaporative emissions system (EVAP) code.
- Ensure the gas cap is properly tightened. Remove it and re-tighten it until it clicks several times.
- After tightening the gas cap, drive the vehicle for a few days to see if the check engine light turns off. The EVAP system may need some time to perform self-diagnostics and clear the code if the gas cap was the only issue.
This method is the least reliable as it relies on the system to self-correct. It doesn’t actively reset the light; it only addresses a potential cause.
Common Causes of a Check Engine Light on a 2019 Toyota Highlander
Several factors can trigger the check engine light on your 2019 Toyota Highlander. Here are some of the most common culprits:
- Loose or Faulty Gas Cap: As mentioned earlier, a loose or damaged gas cap is a frequent cause.
- Faulty Oxygen Sensor: Oxygen sensors monitor the amount of oxygen in the exhaust gases. A malfunctioning oxygen sensor can affect fuel efficiency and emissions.
- Faulty Catalytic Converter: The catalytic converter reduces harmful emissions. A failing catalytic converter can trigger a check engine light and cause the vehicle to fail an emissions test.
- Faulty Mass Airflow (MAF) Sensor: The MAF sensor measures the amount of air entering the engine. A faulty MAF sensor can affect engine performance and fuel efficiency.
- Faulty Spark Plugs or Ignition Coils: Worn or damaged spark plugs or ignition coils can cause engine misfires, triggering the check engine light.
- Vacuum Leaks: Vacuum leaks can disrupt the air-fuel mixture, leading to poor engine performance and a check engine light.
- Faulty Evaporative Emission (EVAP) System Components: The EVAP system prevents fuel vapors from escaping into the atmosphere. Problems with the EVAP system, such as a faulty purge valve or vent valve, can trigger the check engine light.
- Transmission Problems: Although less common, issues within the transmission system can also trigger the check engine light.
When to Seek Professional Help
While you can attempt to reset the check engine light yourself, there are situations where it’s essential to seek professional help from a qualified mechanic.
- If the Check Engine Light is Flashing: As previously mentioned, a flashing check engine light indicates a severe engine misfire and requires immediate attention. Driving with a flashing light can cause significant damage to the catalytic converter.
- If the Check Engine Light Returns Immediately After Resetting: If the check engine light reappears shortly after you reset it, it indicates that the underlying problem hasn’t been resolved. A mechanic can perform a more thorough diagnosis to identify the root cause.
- If You Notice Performance Problems: If the check engine light is accompanied by noticeable performance problems such as rough idling, stalling, reduced power, or unusual noises, it’s best to have the vehicle inspected by a mechanic.
- If You’re Unsure About the Cause: If you’re unable to determine the cause of the check engine light based on the DTCs, it’s wise to consult a mechanic. They have the expertise and equipment to diagnose complex automotive problems.
- Before an Emissions Test: If your vehicle is due for an emissions test, it’s important to address any check engine light issues beforehand. A vehicle with an illuminated check engine light will likely fail the test.
Preventative Maintenance for Your 2019 Toyota Highlander
Regular maintenance is key to preventing check engine light issues and keeping your 2019 Toyota Highlander running smoothly. Here are some essential maintenance tasks:
- Follow the Recommended Maintenance Schedule: Adhere to the maintenance schedule outlined in your Highlander’s owner’s manual. This includes regular oil changes, filter replacements, spark plug replacements, and other essential services.
- Check Fluid Levels Regularly: Monitor the levels of engine oil, coolant, brake fluid, power steering fluid, and transmission fluid. Top up fluids as needed.
- Inspect Hoses and Belts: Regularly inspect hoses and belts for cracks, leaks, or wear. Replace them as necessary.
- Keep the Fuel System Clean: Use quality fuel and consider adding a fuel system cleaner periodically to help remove deposits.
- Properly Maintain the Battery: Keep the battery terminals clean and free of corrosion. Have the battery tested regularly to ensure it’s in good condition.
- Address Minor Issues Promptly: Don’t ignore minor issues such as unusual noises, leaks, or performance problems. Addressing them promptly can prevent them from escalating into more serious and costly repairs.
Final Thoughts
The check engine light on your 2019 Toyota Highlander is a valuable warning signal that shouldn’t be ignored. By understanding its purpose, learning how to access the DTCs, and knowing when to seek professional help, you can effectively address check engine light issues and keep your vehicle running smoothly. Remember, resetting the light is only a temporary solution; it’s crucial to diagnose and resolve the underlying problem to prevent further damage and ensure your Highlander’s longevity. Consistent preventative maintenance is also crucial in mitigating most of the common causes leading to the illumination of the check engine light.
What are some common reasons why the check engine light might come on in my 2019 Toyota Highlander?
A check engine light can illuminate for a variety of reasons, ranging from minor to significant issues. Some common culprits include a loose gas cap, a faulty oxygen sensor, a malfunctioning mass airflow sensor, or problems with the catalytic converter. Addressing these promptly is crucial to prevent potential damage to your vehicle and ensure it runs efficiently.
Ignoring the check engine light can lead to reduced fuel economy, poor performance, and potentially costly repairs down the road. It’s always a good idea to have the code read and diagnosed to determine the root cause of the problem and take appropriate action. Even if you can reset the light, the underlying issue still needs to be resolved.
Can I reset the check engine light on my 2019 Toyota Highlander without a scan tool?
Yes, you can attempt to reset the check engine light without a scan tool, but the effectiveness depends on the cause of the light. The most common method is disconnecting the negative battery cable for a short period. Typically, leaving it disconnected for 15-30 minutes will clear the stored codes in the vehicle’s computer.
However, keep in mind that this method doesn’t address the underlying issue that triggered the light in the first place. While it may temporarily turn off the light, if the problem persists, the light will likely reappear. Furthermore, disconnecting the battery may reset other electronic systems in your Highlander, requiring you to re-enter radio presets or other personalized settings.
How do I use an OBD2 scanner to reset the check engine light on my 2019 Toyota Highlander?
To use an OBD2 scanner, first locate the diagnostic port in your 2019 Toyota Highlander, which is typically located under the dashboard on the driver’s side. Plug the scanner into the port and turn the ignition to the “on” position, but do not start the engine. The scanner will then power on and connect to your vehicle’s computer.
Follow the scanner’s instructions to read the stored trouble codes. Once you’ve noted the codes, navigate to the option to clear or reset the codes. Confirm your selection, and the scanner will send a command to the vehicle’s computer to reset the check engine light. After the process is complete, the light should turn off. If the light returns shortly after, it indicates the underlying issue still needs to be addressed.
What should I do after resetting the check engine light on my 2019 Toyota Highlander?
After resetting the check engine light, it’s essential to monitor your 2019 Toyota Highlander closely. Pay attention to any changes in performance, such as rough idling, decreased fuel economy, or unusual noises. If you experience any of these symptoms, it could indicate that the underlying issue that triggered the check engine light is still present.
Consider driving your Highlander for a few days to see if the check engine light reappears. If it does, it confirms that the problem persists and needs professional attention. In this case, it’s advisable to take your vehicle to a trusted mechanic or Toyota dealer for further diagnosis and repair to prevent potential damage or more costly repairs in the future.
Will resetting the check engine light affect my 2019 Toyota Highlander’s emissions system?
Resetting the check engine light itself doesn’t directly affect the emissions system hardware on your 2019 Toyota Highlander. However, it does clear the diagnostic trouble codes (DTCs) stored in the vehicle’s computer, including those related to emissions system malfunctions. This can affect the readiness monitors.
Readiness monitors are internal tests that the vehicle’s computer performs to ensure the emissions system is functioning correctly. When you reset the check engine light, these monitors are also reset, and the vehicle needs to complete a drive cycle for them to run and confirm the system’s status. If you need to pass an emissions test soon after resetting the light, your vehicle might fail because the monitors haven’t completed their tests.
How long does it take for the check engine light to reappear after resetting it if the problem still exists?
The time it takes for the check engine light to reappear after resetting it varies depending on the nature of the underlying problem. In some cases, the light may come back on almost immediately, especially if the issue is severe or occurs frequently. For example, a consistently misfiring engine will trigger the light very quickly.
In other cases, it might take a few days or even a week for the light to reappear. This is particularly true for intermittent issues or problems that only occur under specific driving conditions. The vehicle’s computer needs to detect the fault again and confirm it before illuminating the check engine light. A thorough inspection by a qualified mechanic can help pinpoint the problem before it leads to further complications.
Is it safe to drive my 2019 Toyota Highlander with the check engine light on?
Driving with the check engine light illuminated can be safe in some situations, but it’s crucial to understand the potential risks involved. If the light is flashing, it usually indicates a more serious problem that could potentially damage your engine or catalytic converter. In such cases, it’s best to avoid driving the vehicle and have it towed to a mechanic for diagnosis.
If the check engine light is on but not flashing, it may indicate a less severe issue, but it’s still important to investigate the cause promptly. Continuing to drive with the light on could lead to further damage and more costly repairs down the road. It’s recommended to have the code read as soon as possible to determine the severity of the problem and take appropriate action.