Resetting the Njoy check engine light is easier than you think—this guide walks you through safe, proven methods. Whether you’ve fixed the issue or just want to clear the warning, we’ll show you how to do it right.
Key Takeaways
- Understand why the light comes on: The check engine light signals a problem with your vehicle’s emissions, engine, or fuel system—don’t ignore it.
- Diagnose before resetting: Always identify and fix the root cause using an OBD2 scanner before clearing the code.
- Use the right tools: An OBD2 scanner is essential for reading and resetting the check engine light on Njoy vehicles.
- Try the battery disconnect method: Disconnecting the car battery for 10–15 minutes can reset the system, but may also erase radio settings.
- Drive cycles matter: After resetting, complete a drive cycle to ensure the system rechecks and confirms no issues remain.
- Avoid repeated resets without repairs: Clearing the light without fixing the problem will only cause it to return—and may lead to bigger issues.
- Seek professional help if needed: If the light keeps coming back, consult a mechanic to avoid long-term damage.
How to Reset Njoy Check Engine Light: A Complete Step-by-Step Guide
So, your Njoy’s check engine light is on—again. It’s annoying, stressful, and maybe a little scary. But don’t panic. In most cases, resetting the check engine light on your Njoy isn’t complicated. With the right tools and a bit of know-how, you can do it yourself in under 30 minutes.
This guide will walk you through everything you need to know: from understanding why the light came on in the first place, to safely resetting it and making sure it doesn’t come back. Whether you’ve already fixed the problem or just want to clear the warning temporarily, we’ve got you covered.
By the end of this guide, you’ll know exactly how to reset the Njoy check engine light, avoid common mistakes, and keep your car running smoothly. Let’s get started.
Why Is the Check Engine Light On?
Before you reset the light, it’s important to understand why it turned on in the first place. The check engine light—also known as the malfunction indicator lamp (MIL)—is part of your car’s onboard diagnostics system (OBD2). It lights up when the system detects a problem that could affect your vehicle’s performance, emissions, or fuel efficiency.
Common causes include:
- A loose or faulty gas cap
- A failing oxygen sensor
- A clogged catalytic converter
- Misfiring spark plugs or ignition coils
- Mass airflow sensor issues
- Evaporative emissions system leaks
Ignoring the light can lead to reduced fuel economy, increased emissions, and even engine damage over time. So, while resetting the light is helpful, it’s only part of the solution. You need to fix the underlying issue first.
Tools You’ll Need to Reset the Njoy Check Engine Light
You don’t need a mechanic’s toolbox to reset the check engine light. Here’s what you’ll need:
1. OBD2 Scanner
This is the most reliable tool for reading and clearing error codes. OBD2 scanners plug into your car’s diagnostic port (usually under the dashboard near the steering wheel) and communicate with the vehicle’s computer.
Look for a basic code reader if you’re on a budget—brands like BlueDriver, Autel, or Ancel offer affordable, user-friendly options. For more advanced diagnostics, consider a Bluetooth scanner that pairs with your smartphone.
2. Owner’s Manual
Your Njoy’s manual will help you locate the OBD2 port and understand specific warning lights or procedures.
3. Safety Gear (Optional)
If you’re disconnecting the battery, wear gloves and safety glasses to protect yourself from accidental sparks or acid.
4. A Quiet, Safe Workspace
Work in a well-lit, flat area—like a garage or driveway—with the engine off and the keys removed.
Step 1: Diagnose the Problem with an OBD2 Scanner
Never reset the check engine light without first diagnosing the issue. Clearing the code without fixing the problem is like turning off a fire alarm while the house is still burning.
Locate the OBD2 Port
In most Njoy models, the OBD2 port is located under the dashboard on the driver’s side. It’s a 16-pin connector, usually black or gray, and looks like a small rectangular slot. If you can’t find it, check near the fuse box or under the steering column.
Plug in the Scanner
Turn off the engine, insert the OBD2 scanner into the port, and turn the ignition to the “ON” position (but don’t start the engine). The scanner should power up and display a menu.
Read the Trouble Codes
Follow the scanner’s instructions to retrieve the diagnostic trouble codes (DTCs). These codes—like P0420 or P0171—tell you exactly what’s wrong. Write them down or take a photo for reference.
Interpret the Codes
Use the scanner’s built-in code library or search online to understand what each code means. For example:
- P0420: Catalyst system efficiency below threshold
- P0171: System too lean (Bank 1)
- P0300: Random/multiple cylinder misfire detected
Once you know the issue, you can decide whether to fix it yourself or take it to a mechanic.
Step 2: Fix the Underlying Issue
Now that you’ve identified the problem, it’s time to fix it. Here are some common fixes:
Tighten or Replace the Gas Cap
A loose or damaged gas cap is one of the most common causes of the check engine light. Simply tighten it until it clicks, or replace it if it’s cracked or worn.
Replace Faulty Sensors
If your scanner shows codes related to the oxygen sensor or mass airflow sensor, you may need to replace them. These parts are relatively inexpensive and can be installed with basic tools.
Address Misfires
Misfire codes often point to bad spark plugs or ignition coils. Replace the affected components and clear the codes.
Check for Vacuum Leaks
A hissing sound under the hood could indicate a vacuum leak. Inspect hoses and connections for cracks or disconnections.
Clean or Replace the Catalytic Converter
If the catalytic converter is clogged, you may need to clean it with a specialized cleaner or replace it entirely. This is a more involved repair—consider professional help.
Once the issue is resolved, you’re ready to reset the check engine light.
Step 3: Reset the Check Engine Light Using an OBD2 Scanner
This is the most reliable and recommended method. It’s fast, safe, and ensures the system is properly reset.
Reconnect the Scanner
With the ignition on (engine off), plug the OBD2 scanner back into the port.
Navigate to the “Clear Codes” Option
Use the scanner’s menu to find the option to clear or erase trouble codes. This is usually labeled “Clear DTCs,” “Erase Codes,” or “Reset MIL.”
Confirm the Reset
The scanner will ask for confirmation. Select “Yes” or “OK.” The device will send a signal to the car’s computer to clear the stored codes and turn off the check engine light.
Verify the Light Is Off
Turn the ignition off, wait 10 seconds, then turn it back on. The check engine light should remain off. If it comes back on immediately, the problem may not be fully resolved.
Alternative Method: Disconnect the Car Battery
If you don’t have an OBD2 scanner, you can try resetting the check engine light by disconnecting the car battery. This method forces the car’s computer to reset, but it’s less precise and may erase other settings.
Turn Off the Engine and Remove the Keys
Make sure the car is completely off and the keys are out of the ignition.
Locate the Battery
Open the hood and find the battery. In most Njoy models, it’s on the right side of the engine bay.
Disconnect the Negative Terminal
Use a wrench to loosen the nut on the negative (black) battery terminal. Carefully remove the cable and tuck it away from the battery to prevent accidental contact.
Wait 10–15 Minutes
This gives the car’s computer time to fully discharge and reset. Some experts recommend waiting up to 30 minutes for a complete reset.
Reconnect the Battery
Reattach the negative terminal and tighten the nut securely.
Turn On the Ignition
Start the car and check if the check engine light is off. If it is, great! If not, the issue may still exist.
Note the Side Effects
Disconnecting the battery may reset your radio presets, clock, and anti-theft system. You may need to re-enter security codes or reprogram key fobs.
Step 4: Complete a Drive Cycle
After resetting the light, your car’s computer needs to run a series of self-tests to ensure everything is working properly. This is called a “drive cycle.”
A drive cycle typically includes:
- Starting the engine when cold
- Driving at varying speeds (city and highway)
- Accelerating and decelerating smoothly
- Letting the engine idle for a few minutes
The exact drive cycle varies by model, but a general pattern is:
- Start the car and let it idle for 2–3 minutes.
- Drive at 30–40 mph for 5 minutes.
- Accelerate to 55–60 mph and maintain speed for 10 minutes.
- Slow down and stop, then idle for 2 minutes.
- Repeat if necessary.
After completing the drive cycle, the car’s computer will recheck all systems. If no issues are found, the check engine light should stay off.
Troubleshooting: What If the Light Comes Back On?
If the check engine light returns after resetting, don’t panic—but don’t ignore it either. Here’s what to do:
Recheck the Codes
Use your OBD2 scanner to read the new codes. The problem may have worsened or a different issue may have developed.
Inspect Recent Repairs
Did you recently replace a part? Make sure it was installed correctly and is compatible with your Njoy.
Check for Intermittent Issues
Some problems, like loose wiring or minor sensor glitches, only appear under certain conditions. Monitor the car’s behavior and note any patterns.
Consult a Mechanic
If you’ve tried everything and the light keeps coming back, it’s time to see a professional. They have advanced tools and experience to diagnose complex issues.
Safety Tips and Best Practices
Resetting the check engine light is generally safe, but follow these tips to avoid problems:
- Never reset the light without diagnosing the issue first. You could miss a serious problem.
- Use quality tools. Cheap scanners may give inaccurate readings.
- Keep records. Save your trouble codes and repair notes for future reference.
- Don’t ignore recurring lights. Repeated warnings often indicate a deeper issue.
- Follow your owner’s manual. It contains model-specific guidance for your Njoy.
When to See a Mechanic
While many check engine light issues can be handled at home, some require professional attention. See a mechanic if:
- The light is flashing (this indicates a severe misfire that can damage the catalytic converter)
- You’re unsure how to interpret or fix the code
- The problem involves the transmission, fuel system, or electrical components
- You’ve tried multiple fixes and the light keeps returning
Conclusion
Resetting the Njoy check engine light doesn’t have to be intimidating. With an OBD2 scanner, a little patience, and the right approach, you can clear the warning and get back on the road with confidence.
Remember: the light is there for a reason. Always diagnose the problem first, fix it properly, and then reset the system. Skipping steps might give you temporary relief, but it won’t solve the real issue—and could cost you more in the long run.
By following this guide, you’ll not only reset the check engine light but also gain a better understanding of your car’s health. Stay proactive, stay informed, and keep your Njoy running smoothly for years to come.