The check engine light on your 2019 Toyota Highlander can be both a helpful diagnostic tool and a source of frustration. While it’s a valuable indicator of potential issues affecting your vehicle’s performance, fuel efficiency, or emissions, it can also occasionally stay illuminated even after a problem has been resolved. If you’ve addressed the underlying cause and now need to reset the check engine light, understanding the correct procedures is essential to ensure your vehicle runs smoothly and passes emissions inspections.
In this detailed guide, we will walk you through multiple methods to reset the check engine light on a 2019 Toyota Highlander, explain why the light may come on, and offer tips for maintaining engine health. Whether you’re a seasoned driver or new to vehicle maintenance, this guide is designed to be both informative and practical.
Understanding Why the Check Engine Light Comes On
Before diving into the reset process, it’s crucial to understand what triggers the check engine light (CEL). In your 2019 Toyota Highlander, the CEL is part of the onboard diagnostics system — commonly referred to as OBD-II — which continuously monitors critical engine systems.
When one of these systems operates outside of factory-set parameters or a malfunction occurs, the system logs a diagnostic trouble code (DTC) and illuminates the check engine light.
Common issues that cause the check engine light to illuminate include:
- A loose gas cap: One of the most frequent and easiest-to-fix causes.
- Faulty oxygen (O2) sensor: Affects engine efficiency and fuel economy.
- Spark plug issues: Leads to poor engine performance and misfires.
- Catalytic converter problems: May result in environmental regulation violations and increased emission levels.
- Bad mass airflow (MAF) sensor: Can cause difficulty starting the engine and reduced fuel efficiency.
It is strongly advised that you diagnose the trouble code(s) using an OBD-II scanner before attempting to reset the light. This ensures any underlying issue is addressed, preventing potential damage and recurring problems.
Why Resetting the Check Engine Light Matters
There are several reasons why resetting the check engine light is important:
- To clear the warning after completing repairs.
- To ensure your vehicle passes emissions testing.
- To prevent the light from distracting or confusing drivers.
- To satisfy dealership or mechanic follow-ups after service.
However, remember that resetting the CEL does not fix the underlying problem. It simply acknowledges that the issue has been addressed and allows the engine control module (ECM) to begin its monitoring process again.
Methods to Reset the Check Engine Light on a 2019 Toyota Highlander
There are three primary ways to reset the check engine light on your 2019 Toyota Highlander:
- Using an OBD-II scanner (recommended).
- Disconnecting the battery (not always effective and may cause other system resets).
- Letting it reset naturally (on some models, the light goes off after driving cycles).
Each of these methods has pros and cons. Let’s explore each in detail.
Method 1: Using an OBD-II Code Reader or Scanner
This is the most reliable and preferred method, especially if you’ve just completed a repair and want to verify that the system has reset properly.
Here’s how to do it:
Step 1: Get an OBD-II Scanner
Purchase a basic OBD-II scanner if you don’t already own one. Reputable brands include:
- Autel AutoLink AL539
- Innova 3160g
- BlueDriver Pro OBD2 Scanner
These scanners vary in price and features but all can read and clear codes.
Step 2: Locate the OBD-II Port
Your 2019 Toyota Highlander’s OBD-II port is typically located under the dashboard on the driver’s side, within easy reach from the driver’s seat. It’s usually a 16-pin connector.
Step 3: Plug in the Scanner
Insert the scanner into the OBD-II port. No tools are required. Once connected, turn your ignition key to the “ON” position, but do not start the engine.
Step 4: Switch On the Scanner
Power the device on. Most will automatically detect the vehicle once powered up. Follow the on-screen prompts to initiate the diagnostics.
Step 5: Retrieve and Record Any Trouble Codes
Even if you’ve completed a repair, reading the codes ensures that you addressed the correct issue. You can look up the codes to understand the nature of prior malfunctions.
Step 6: Clear the Codes
There should be an option in the scanner’s menu labeled “Clear Codes” or “Reset Check Engine Light.” Select that option and follow the instructions. A confirmation message should indicate success.
Step 7: Test Drive the Vehicle
After clearing codes, take your Toyota Highlander for a drive to allow the system to re-establish normal sensor readings and emission control functions.
Step 8: Re-Scan to Verify
After a day or so, reinsert the scanner to ensure no codes have returned.
Method 2: Manually Disconnecting the Battery
While this method can work, it’s not the best option due to its less predictable results and the side effects it can cause.
Why It Can Be Problematic
- Risk of data loss: Disconnecting the battery may reset driver preferences, clock settings, and even tire pressure monitoring systems.
- Incomplete code erasure: On some vehicles, including the 2019 Highlander, simply disconnecting the battery might not fully reset the engine light.
- Could initiate a diagnostic reset: The engine control module might still record codes after reconnecting power.
If you still choose to disconnect the battery, here’s how:
Step 1: Turn Off the Ignition
Ensure your vehicle is off and all accessories are shut down.
Step 2: Locate the Battery
In most 2019 Highlander models, the battery is under the hood on the driver’s side near the windshield.
Step 3: Remove the Battery Cables
Start by disconnecting the negative terminal first (black and marked with a minus sign). Then remove the positive terminal. Let the terminals sit disconnected for about 15 minutes to ensure a full reset of the electronic control unit (ECU).
Step 4: Reconnect the Battery
Reconnect the positive terminal first, followed by the negative terminal. Ensure all connections are tight.
Step 5: Start the Vehicle and Monitor
Let your Highlander idle for a few minutes. After driving a short distance, observe if the check engine light returns.
In many cases, you’ll notice that while the light may turn off, it can reappear after driving if the problem wasn’t resolved or the sensors haven’t fully adapted.
Method 3: Allow the System to Reset on Its Own
After repairs, the check engine light may reset itself after several driving cycles, especially if the underlying issue has been fixed.
Toyota’s engine computer performs a series of readiness monitors during normal operation, and once satisfied that the component or system in question is working correctly, the light can turn off automatically.
But this process can take anywhere from:
- 10 minutes to 100 miles of driving
- Dependent on driving behavior and environmental conditions
To hasten this process:
– Perform mixed driving (highway and city)
– Allow the engine to warm up fully
– Avoid short trips and frequent cold starts
– Don’t ignore repeated illumination after initial clearing
This method is best when you’re confident the issue is solved and don’t want to invest in a scanner.
Diagnosing the Problem Before Resetting
It’s critical that you determine why the check engine light came on in the first place. Simply resetting the light and ignoring a potentially serious issue can lead to:
- Costly engine damage
- Poor fuel economy
- Failed emissions tests
- Increased pollution output
When you use an OBD-II scanner to read the code, you typically receive standardized codes (e.g., P0171, P0420, P0300), which translate to specific malfunctions.
Here is a brief breakdown of common codes you might see:
| Trouble Code | Description | Potential Fix |
|---|---|---|
| P0171 | System Too Lean (Bank 1) | Check MAF sensor, vacuum leaks, or fuel delivery system |
| P0420 | Catalyst System Efficiency Below Threshold | Exhaust system inspection or catalytic converter replacement |
| P0300 | Random/Multiple Cylinder Misfire Detected | Inspect spark plugs, coils, or fuel injectors |
| P0440 | Evaporative Emissions Control System Fault | Loose gas cap or leaking fuel system hose |
| P0135 | O2 Sensor Heater Circuit Malfunction | Faulty or outdated oxygen sensor |
Reading these codes allows you to pinpoint specific areas where maintenance or repairs are needed.
Additional Tips for Resetting the Check Engine Light
Here are some best practices that can increase your chances of fully resetting the check engine light on your Toyota Highlander:
Clear Codes and Reset Drive Cycles
Even after clearing codes, the ECU must verify that everything is working properly through a series of drive cycles. A typical drive cycle for a Toyota includes:
- Cold start (engine at normal ambient temp)
- Idling at operating temperature
- Accelerating from 0–50 mph and then coasting
- Highway driving at steady speed for 10+ minutes
Following a proper drive cycle ensures that emission monitors are reset, allowing your car to pass an emissions test.
Consider Visiting a Professional Mechanic
While DIY methods are cost-effective, complex engine issues — especially those involving P0420, P0300, or electrical faults — may require a professional diagnosis. Toyota dealerships and qualified mechanics can use factory-level scanners and software to:
– Clear pending codes
– Re-calibrate engine control units
– Perform readiness tests
Moreover, if your check engine light reappears shortly after a reset, a mechanic can help identify systemic issues or hard-to-diagnose faults.
Reset Engine Light at Dealer Facilities
If your Highlander is still under warranty or scheduled service coverage, visiting your local Toyota dealership can be an effective option. Technicians regularly reset CELs as part of repair processes and can ensure that your car is up to factory specifications.
Preventative Measures: Avoiding Future CEL Activations
To keep your 2019 Toyota Highlander in top condition and avoid unnecessary check engine light activations, consider the following:
Maintain a Regular Maintenance Schedule
Toyota recommends several key services during your Highlander’s life:
- Oil changes every 5,000–10,000 miles
- Spark plug replacement every 120,000 miles
- Air and cabin filter replacements every 15,000–30,000 miles
- Timing belt inspection at regular intervals (timing chain in some models)
Ignoring regular maintenance invites the risk of engine malfunctions and sensor degradation.
Maintain Proper Fuel and Fluids
Always:
- Use the recommended octane level (regular unleaded is sufficient for the 2019 Highlander)
- Check coolant and transmission fluid levels
- Refuel with a tight gas cap to prevent EVAP system issues
Drive Responsibly
Excessive idling, rapid acceleration, and frequent short trips can place undue stress on the engine, emissions system, and related sensors.
Invest in Quality Parts
If you perform your own repairs:
– Use OEM (original equipment manufacturer) or high-quality aftermarket parts
– Replace spark plugs, coils, O2 sensors, and MAF sensors promptly when diagnostics suggest failure
– Always reset the system after completing repairs
Conclusion
Resetting the check engine light on your 2019 Toyota Highlander doesn’t have to be a mystery. Whether you’re a do-it-yourselfer with an OBD-II scanner or prefer the simplicity of driving cycles, the key behind any successful reset is a clear understanding of the underlying cause and a systematic approach to correction.
Remember, the check engine light is a smart system designed to enhance engine performance and protect the environment. While it can be annoying, it plays a vital role in keeping your Highlander safe and efficient.
By following the steps outlined in this guide, you can confidently reset the CEL, monitor your vehicle’s performance, and enjoy a smoother and more assured driving experience.
Always prioritize vehicle diagnostics before resets, drive thoughtfully, and maintain your car well — and you’ll enjoy many more years of reliable service from your 2019 Toyota Highlander.
What does the Check Engine Light on a 2019 Toyota Highlander indicate?
The Check Engine Light on a 2019 Toyota Highlander is a warning indicator that signals a potential problem with the vehicle’s engine or emissions system. This light can come on for a wide range of reasons, from something as simple as a loose gas cap to more serious mechanical or electronic engine issues. When illuminated, the engine control unit (ECU) records a diagnostic trouble code (DTC), which can be read with a specialized OBD-II scanner to help determine the cause of the problem.
It’s important to note that the Check Engine Light does not always mean an immediate emergency, but it should never be ignored. If the light is steady, it often indicates a less urgent issue; however, a flashing light generally means a severe misfire that could damage the catalytic converter or lead to further engine damage. Owners should consult a professional or use a reliable method to read and address the corresponding fault code before attempting to reset the light.
Can I reset the Check Engine Light myself on a 2019 Toyota Highlander?
Yes, you can reset the Check Engine Light on a 2019 Toyota Highlander by yourself, provided the issue that caused the light to come on has already been resolved. Simply resetting the light without addressing the underlying problem may temporarily turn it off, but it will likely return once the vehicle’s onboard diagnostics detect the fault again. Common methods of resetting the Check Engine Light include using an OBD-II scanner, disconnecting the battery, or letting the car’s computer reset automatically after a period of driving.
However, performing a DIY reset should always follow a diagnostic process to ensure that all vehicle systems are functioning properly. If you’re unsure about the cause of the Check Engine Light, it’s wise to visit a certified mechanic or use a code reader to identify and correct the issue before attempting any reset. In some cases, tampering with the ECU without addressing the root cause can lead to emissions test failures or void warranties.
What tools do I need to reset the Check Engine Light on my 2019 Toyota Highlander?
To reset the Check Engine Light on a 2019 Toyota Highlander, you may need tools such as an OBD-II code scanner, which is the most reliable method for both diagnosing and resetting the light. These scanners plug into the vehicle’s OBD-II port, typically located beneath the dashboard on the driver’s side, and allow you to read and clear fault codes. Some popular scanners can even provide a description of the trouble code and potential solutions.
Alternatively, you might use a basic toolkit if opting for other methods like disconnecting the vehicle’s battery. In this case, you would need a wrench to remove the negative terminal and precautions such as wearing gloves to protect your hands. For those unfamiliar with vehicle systems, an OBD-II scanner is recommended for a more accurate and safe approach, allowing the user to monitor live vehicle data and ensure all systems have returned to normal operation.
How do I use an OBD-II scanner to reset the Check Engine Light?
Using an OBD-II scanner to reset the Check Engine Light on your 2019 Toyota Highlander is a straightforward process. First, locate the OBD-II port under the dashboard near the steering column and plug the scanner into it. Turn the vehicle’s ignition on, but do not start the engine. Then, power on the scanner and follow the on-screen prompts to establish a connection with the vehicle’s onboard computer. Once connected, navigate the scanner menu to the “Read Codes” option to retrieve any stored diagnostic trouble codes (DTCs).
After reviewing the codes and ensuring the related issues have been fixed, proceed to the “Clear Codes” function on the scanner. This should erase the stored codes and deactivate the Check Engine Light. However, it’s important to note that the vehicle’s ECU may not turn off the light immediately and may require driving under normal conditions for a few cycles for the system to reset completely. Also, ensure your scanner is compatible with modern vehicles like the 2019 Toyota Highlander and always verify that the engine operates correctly post-reset.
Will disconnecting the battery reset the Check Engine Light on a 2019 Toyota Highlander?
Yes, disconnecting the battery can reset the Check Engine Light on a 2019 Toyota Highlander by clearing the vehicle’s ECU memory. This method involves turning off the engine, locating the battery under the hood, and disconnecting the negative terminal using a wrench. For best results, wait for at least 15 minutes before reconnecting the battery to allow the vehicle’s computer to fully reset and clear any stored fault codes.
However, this approach has drawbacks. It can erase other important vehicle settings, such as radio presets and ECU-calibrated driving data, which may result in altered engine performance until the system relearns your driving habits. Additionally, disconnecting the battery does not guarantee a permanent fix if the issue persists, and the Check Engine Light might reappear after a cycle of driving. It’s generally less precise than using an OBD-II scanner and should be used with caution.
Can the Check Engine Light reset itself on the 2019 Toyota Highlander?
The Check Engine Light on a 2019 Toyota Highlander can reset itself if the issue that triggered the light has been resolved and the vehicle’s engine control unit (ECU) completes a sufficient number of successful driving cycles. This means you’ll need to drive the car under normal conditions for a few days to a week, allowing the ECU to monitor all systems and confirm normal operation. Once the system confirms that the condition no longer exists, the light will turn off automatically, and the relevant codes can be cleared from the ECU.
For the self-reset to occur, the vehicle must complete its internal OBD-II drive cycle, which involves driving at varying speeds, starting the car when it’s cold, and running the engine under different loads. This process can differ based on the root cause of the trouble code. Some codes might reset faster than others, depending on the nature of the malfunction. If the light remains on after completing multiple drive cycles, it’s likely that the issue has not been fully resolved and should be addressed.
What should I do if the Check Engine Light comes back on after resetting?
If the Check Engine Light returns after you’ve reset it on your 2019 Toyota Highlander, it means the underlying problem likely persists. The first step is to use an OBD-II scanner to check for any diagnostic trouble codes (DTCs) to identify the specific fault. If you addressed a known issue, ensure that all components related to it are functioning correctly and that the problem hasn’t returned due to improper repair or calibration.
Persistent Check Engine Lights could indicate recurring mechanical or sensor problems, faulty aftermarket accessories, or even intermittent issues that are harder to diagnose. It’s advisable to bring your vehicle to a certified Toyota technician or an experienced mechanic who can perform a thorough diagnostic. Further investigation may require advanced tools or inspection of the emissions system, engine components, or wiring harnesses. Ignoring the issue could lead to degraded fuel economy, rough vehicle operation, or expensive repairs down the line.