Resetting the check engine light on a 1999 Honda is a straightforward process, but it should only be done after diagnosing and fixing the underlying issue. This guide walks you through safe methods, including battery disconnection and OBD2 code clearing, with clear steps and expert tips.
Key Takeaways
- Diagnose the problem first: Never reset the light without identifying and fixing the root cause using an OBD2 scanner or professional help.
- Use a scan tool for best results: An OBD2 scanner is the safest and most reliable way to clear codes and reset the light on a 1999 Honda.
- Battery disconnection works but has drawbacks: Disconnecting the battery can reset the light, but it also erases radio settings, clock, and learned engine parameters.
- Drive cycle may be required: After resetting, your Honda may need a short drive to complete system checks before the light stays off.
- Check for persistent issues: If the light returns, the problem wasn’t fully resolved—seek professional diagnosis.
- Avoid quick fixes that mask problems: Simply clearing codes without repairs can lead to emissions failures or engine damage.
- Keep records of repairs: Document any fixes made so you can reference them during future maintenance or inspections.
How to Reset Check Engine Light on 1999 Honda
If you’ve recently fixed an issue with your 1999 Honda and the check engine light is still on, you’re not alone. Many drivers face this frustrating situation—especially with older vehicles like the 1999 Honda Civic, Accord, or CR-V. The good news? Resetting the check engine light is possible, and in most cases, fairly simple. But before you jump into clearing that warning light, it’s crucial to understand what it means and why it came on in the first place.
In this comprehensive guide, we’ll walk you through everything you need to know about resetting the check engine light on a 1999 Honda. You’ll learn how to safely diagnose the problem, choose the best reset method, and ensure the light stays off for good. Whether you’re a DIY enthusiast or just trying to pass your next emissions test, this step-by-step tutorial will give you the confidence and knowledge to handle it like a pro.
We’ll cover multiple reset methods—from using an OBD2 scanner to disconnecting the battery—and explain the pros and cons of each. You’ll also get practical tips, troubleshooting advice, and answers to common questions. By the end, you’ll know exactly how to reset the check engine light on your 1999 Honda without risking further damage or voiding your warranty.
Let’s get started.
Why the Check Engine Light Comes On
Visual guide about How to Reset Check Engine Light on 1999 Honda
Image source: hondaaccordforum.com
Before you reset the check engine light, it’s essential to understand why it illuminated in the first place. The check engine light—also known as the malfunction indicator lamp (MIL)—is part of your Honda’s onboard diagnostics system (OBD2). This system monitors various components of your engine and emissions system, including the oxygen sensors, catalytic converter, fuel system, and ignition system.
When the computer detects a problem—such as a misfire, faulty sensor, or emissions leak—it stores a diagnostic trouble code (DTC) and turns on the check engine light to alert you. On a 1999 Honda, this system is fully OBD2 compliant, meaning it uses standardized codes that can be read by most modern scan tools.
Common reasons the check engine light comes on in a 1999 Honda include:
- A loose or missing gas cap
- Faulty oxygen (O2) sensor
- Worn spark plugs or ignition coils
- Catalytic converter issues
- Mass airflow (MAF) sensor problems
- Evaporative emissions (EVAP) system leaks
Ignoring the light can lead to reduced fuel efficiency, increased emissions, and even engine damage over time. That’s why it’s critical to diagnose the issue before resetting the light. Simply clearing the code without fixing the problem is like turning off a smoke alarm while the fire still burns—it doesn’t solve the real issue.
Tools You’ll Need
To reset the check engine light on your 1999 Honda, you’ll need a few basic tools. The exact items depend on the method you choose, but here’s a list of what’s commonly used:
- OBD2 scan tool: This is the most reliable and recommended tool. It plugs into your car’s diagnostic port and allows you to read and clear trouble codes. Many affordable models are available online or at auto parts stores.
- Wrench or socket set: Needed if you plan to disconnect the battery.
- Safety gloves and glasses: Always protect yourself when working under the hood.
- Owner’s manual: Helpful for locating the diagnostic port and understanding your Honda’s specific systems.
- Notepad and pen: To record trouble codes and repair notes.
If you don’t own an OBD2 scanner, don’t worry. Many auto parts stores—like AutoZone, O’Reilly, or Advance Auto Parts—offer free code reading services. They’ll plug in their scanner, tell you what the code means, and sometimes even help you clear it.
Method 1: Using an OBD2 Scan Tool (Recommended)
The safest and most effective way to reset the check engine light on a 1999 Honda is by using an OBD2 scan tool. This method allows you to read the trouble codes, understand the problem, and clear the light without affecting other systems in your vehicle.
Step 1: Locate the OBD2 Port
The OBD2 diagnostic port on a 1999 Honda is usually located under the dashboard on the driver’s side. It’s a 16-pin connector, often tucked behind a small panel or near the steering column. You may need to crouch down and look up under the dash to find it. It’s typically black or gray and shaped like a trapezoid.
If you’re having trouble locating it, consult your owner’s manual or look for a label that says “OBD2” or “DLC” (Data Link Connector).
Step 2: Plug in the Scan Tool
Turn off the ignition, then plug the OBD2 scanner into the port. Make sure it’s securely connected. Some scanners will power on automatically when plugged in, while others require you to turn the ignition to the “ON” position (without starting the engine).
Step 3: Read the Trouble Codes
Follow the scanner’s instructions to read the stored trouble codes. Most scanners will display a code like “P0420” or “P0171.” Write down the code(s) so you can research what they mean. You can look them up online or use the scanner’s built-in code library.
For example:
- P0420: Catalyst system efficiency below threshold
- P0171: System too lean (fuel trim)
- P0301: Cylinder 1 misfire detected
Understanding the code helps you determine whether the issue has been properly repaired. If you’ve already fixed the problem—like replacing a faulty O2 sensor—you can proceed to clear the code.
Step 4: Clear the Codes
Once you’ve confirmed the repair is complete, use the scanner to clear the trouble codes. Look for a button or menu option labeled “Clear Codes,” “Erase Codes,” or “Reset.” Press it, and the scanner will send a signal to the car’s computer to delete the stored codes.
After clearing, the check engine light should turn off. If it doesn’t, double-check that the scanner is functioning properly and that the ignition is in the correct position.
Step 5: Verify the Reset
Start the engine and let it run for a few minutes. The check engine light should remain off. If it comes back on, the problem may not be fully resolved, or a new issue has developed.
It’s also a good idea to take your Honda for a short drive—about 10 to 15 minutes—to allow the onboard computer to complete its self-checks (called a drive cycle). This ensures all systems are functioning properly and helps prevent the light from returning.
Method 2: Disconnecting the Battery
If you don’t have access to an OBD2 scanner, you can reset the check engine light by disconnecting the car’s battery. This method forces the vehicle’s computer to reset by cutting power to its memory. However, it comes with some drawbacks, so use it with caution.
Step 1: Turn Off the Engine and Remove the Key
Make sure the engine is off and the key is removed from the ignition. This prevents any electrical surges or accidental starts.
Step 2: Locate the Battery
Open the hood and locate the battery. On most 1999 Honda models, it’s in the engine bay on the driver’s side.
Step 3: Disconnect the Negative Terminal
Using a wrench or socket, loosen the nut on the negative (black) battery terminal. Carefully remove the cable and tuck it away from the battery so it doesn’t accidentally touch the terminal.
Important: Always disconnect the negative terminal first to avoid short circuits.
Step 4: Wait 15–30 Minutes
Leave the battery disconnected for at least 15 to 30 minutes. This allows the car’s computer (ECU) to fully discharge and reset. Some mechanics recommend waiting up to an hour for a complete reset.
Step 5: Reconnect the Battery
After waiting, reconnect the negative terminal and tighten the nut securely. Make sure the connection is tight to prevent electrical issues.
Step 6: Start the Engine
Turn the ignition to the “ON” position and wait a few seconds. Then start the engine. The check engine light should be off. If it comes back on, the underlying issue may still exist.
Drawbacks of Battery Disconnection
While this method works, it has some downsides:
- Resets radio and clock: You’ll need to reset your radio presets, clock, and possibly the trip odometer.
- Erases learned engine data: The ECU stores adaptive learning data over time. Resetting it may cause rough idling or poor performance until the system relearns.
- Doesn’t fix the problem: If the original issue isn’t repaired, the light will likely return.
For these reasons, using an OBD2 scanner is generally preferred.
Method 3: Driving to Reset the Light
In some cases, the check engine light may turn off on its own after the problem is fixed—especially if it was a minor issue like a loose gas cap. This is because the Honda’s onboard computer continuously monitors systems and will clear the light if no faults are detected during a drive cycle.
A drive cycle is a specific pattern of driving that allows the ECU to test various emissions and engine systems. For a 1999 Honda, a typical drive cycle includes:
- Starting the engine when cold
- Driving at varying speeds (city and highway)
- Accelerating and decelerating smoothly
- Letting the engine reach normal operating temperature
If you’ve fixed the issue—such as tightening the gas cap—try driving your Honda for 30 to 50 miles over a few days. The light may turn off automatically.
However, this method is unreliable for serious problems. If the light remains on after a week of normal driving, use a scan tool or battery reset.
Troubleshooting Common Issues
Even after resetting the check engine light, you might run into problems. Here’s how to handle common scenarios:
The Light Comes Back On
If the check engine light returns shortly after resetting, the original problem wasn’t fully resolved. For example:
- A new O2 sensor may be faulty
- A vacuum leak might still exist
- The catalytic converter could be failing
Use an OBD2 scanner to read the new code and diagnose the issue. Don’t ignore recurring lights—they often indicate serious problems.
The Light Flashes
A flashing check engine light is more urgent than a steady one. It usually indicates a severe misfire that can damage the catalytic converter. If your light is flashing:
- Reduce speed and avoid heavy acceleration
- Pull over safely if the engine feels rough
- Have the car towed to a mechanic if necessary
Flashing lights should never be ignored.
Radio or Clock Resets After Battery Disconnect
This is normal. After reconnecting the battery, use your owner’s manual to reset the radio presets and clock. Some Hondas require a security code to unlock the radio—check your manual or contact a dealer if needed.
Engine Runs Rough After Reset
If your Honda idles roughly or hesitates after a battery reset, the ECU may need time to relearn driving patterns. Drive normally for a few days, and the issue should resolve. If not, there may be an underlying mechanical problem.
Safety Tips and Best Practices
When working on your 1999 Honda, keep these safety tips in mind:
- Always wear safety glasses and gloves. Battery acid and electrical components can be hazardous.
- Work in a well-ventilated area. Avoid enclosed spaces when working with batteries.
- Don’t touch both battery terminals at once. This can cause a short circuit or shock.
- Use the correct tools. A wrench that’s too big can strip the battery terminals.
- Keep a fire extinguisher nearby. Just in case.
Also, remember that resetting the check engine light doesn’t fix the problem—it only clears the warning. Always address the root cause to avoid future issues.
When to See a Mechanic
While many check engine light issues can be handled at home, some problems require professional help. See a certified mechanic if:
- The light is flashing
- You’re unable to read or clear the code
- The problem involves the transmission, engine internals, or emissions system
- You’ve tried multiple fixes and the light keeps returning
- You’re unsure about the diagnosis
A professional mechanic has advanced tools and experience to accurately diagnose and repair complex issues.
Conclusion
Resetting the check engine light on a 1999 Honda is a manageable task, but it should never be done without first understanding and addressing the underlying issue. Whether you use an OBD2 scanner, disconnect the battery, or rely on a drive cycle, the key is to ensure the problem is truly fixed.
The OBD2 scan tool method is the most reliable and recommended approach. It allows you to read codes, confirm repairs, and clear the light safely—without affecting other systems. Battery disconnection works in a pinch but comes with trade-offs like lost radio settings and ECU relearning.
Always prioritize safety, use the right tools, and don’t ignore persistent or flashing lights. With the knowledge from this guide, you can confidently reset your check engine light and keep your 1999 Honda running smoothly for years to come.
Remember: a cleared light is only the first step. Regular maintenance, timely repairs, and attentive driving will keep your Honda in top shape—and that warning light off for good.