Resetting the check engine light on a 1999 Honda Civic can be done easily at home using basic tools or an OBD2 scanner. This guide walks you through safe, step-by-step methods to clear the light after fixing the underlying issue.
Key Takeaways
- Always diagnose the problem first: The check engine light indicates a real issue—don’t reset it without fixing the root cause.
- Use an OBD2 scanner for accuracy: This tool reads trouble codes and safely resets the light without risking electrical damage.
- Battery disconnection works but has drawbacks: It resets the light but also clears radio settings, clock, and ECU adaptations.
- Drive cycle completion may be needed: Some systems require driving under specific conditions before the light stays off.
- Avoid quick-fix myths: Spraying cleaner into the gas tank or tapping sensors won’t fix real problems or reset the light permanently.
- Check fuses and connections: A loose gas cap or blown fuse can trigger the light—verify these before resetting.
- Monitor after reset: If the light returns, the issue persists and needs professional diagnosis.
How to Reset Check Engine Light on Honda Civic 1999
If you’ve recently fixed an issue with your 1999 Honda Civic—like replacing a faulty oxygen sensor, tightening a loose gas cap, or repairing a vacuum leak—you might notice the check engine light is still on. That’s normal. The light doesn’t automatically turn off just because the problem is resolved. You need to reset it manually.
In this guide, you’ll learn how to reset the check engine light on a 1999 Honda Civic using safe, proven methods. Whether you’re a DIY enthusiast or a first-time car owner, these steps are simple, cost-effective, and don’t require advanced mechanical skills. We’ll cover everything from using an OBD2 scanner to disconnecting the battery, plus troubleshooting tips to ensure the light stays off.
By the end of this guide, you’ll know exactly what tools to use, how to avoid common mistakes, and when it’s time to visit a mechanic. Let’s get started.
Why the Check Engine Light Comes On
Visual guide about How to Reset Check Engine Light on Honda Civic 1999
Image source: hondacheckenginelight.com
Before resetting 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). In the 1999 Honda Civic, this system monitors engine performance, emissions, fuel efficiency, and various sensors.
When something goes wrong—like a misfire, low fuel pressure, or a faulty catalytic converter—the engine control unit (ECU) detects the issue and stores a trouble code. It then triggers the check engine light to alert you.
Common causes in a 1999 Honda Civic include:
– Loose or damaged gas cap
– Faulty oxygen (O2) sensor
– Mass airflow (MAF) sensor issues
– Spark plug or ignition coil problems
– Exhaust gas recirculation (EGR) valve failure
– Catalytic converter inefficiency
Important: Never reset the light without addressing the underlying problem. Doing so is like turning off a smoke alarm while your house is still on fire. The light will likely come back on, and you could risk further damage to your engine or emissions system.
Tools You’ll Need
You don’t need a full garage of tools to reset the check engine light. Here’s what you’ll need depending on the method you choose:
- OBD2 scanner: A handheld device that plugs into your car’s diagnostic port. Affordable options start around $20–$30 and can read and clear codes.
- Wrench or socket set: For disconnecting the battery (usually a 10mm wrench).
- Safety gloves and glasses: Always protect yourself when working under the hood.
- Owner’s manual: Helps locate the diagnostic port and fuse box.
- Flashlight: Useful for seeing in tight spaces under the dashboard.
If you don’t own an OBD2 scanner, consider borrowing one from an auto parts store (many offer free code reading) or purchasing a basic model. It’s a worthwhile investment if you plan to maintain your car yourself.
Method 1: Using an OBD2 Scanner (Recommended)
The safest and most effective way to reset the check engine light is with an OBD2 scanner. This method allows you to read the trouble code, confirm the issue is fixed, and clear the light without affecting other systems.
Step 1: Locate the OBD2 Port
In the 1999 Honda Civic, the OBD2 diagnostic port is located under the dashboard on the driver’s side. It’s a 16-pin connector, usually black or gray, and shaped like a trapezoid.
To find it:
– Sit in the driver’s seat and look under the steering column.
– You may need to crouch down or use a flashlight.
– It’s often near the fuse box or behind a small panel.
Tip: If you can’t see it, check your owner’s manual or look for a small cover labeled “OBD” or “DIAG.”
Step 2: Plug in the OBD2 Scanner
Once you’ve found the port:
– Turn off the ignition.
– Plug the scanner’s connector into the OBD2 port. It only fits one way, so don’t force it.
– Turn the ignition to the “ON” position (but don’t start the engine). This powers the scanner and ECU.
Most scanners will display a welcome screen or prompt you to select a language. Follow the on-screen instructions.
Step 3: Read the Trouble Code
Before clearing the light, use the scanner to read the stored trouble code(s). This confirms what issue triggered the light.
– Press the “Read” or “Scan” button on the device.
– The scanner will display a code like “P0420” (catalytic converter efficiency) or “P0171” (system too lean).
– Write down the code and research it online or in a repair manual.
Example: If the code is P0457, it likely means your gas cap is loose or damaged. Tighten or replace it before resetting.
Step 4: Clear the Code and Reset the Light
After fixing the issue:
– On the scanner, select “Clear Codes” or “Erase DTCs.”
– Confirm the action when prompted.
– The scanner will send a signal to the ECU to turn off the check engine light.
Turn off the ignition, unplug the scanner, and start the car. The light should be off.
Note: Some scanners also let you view live data (like engine RPM or oxygen sensor readings), which can help verify the repair worked.
Method 2: Disconnecting the Battery
If you don’t have an OBD2 scanner, you can reset the check engine light by disconnecting the car battery. This method forces the ECU to reset, clearing stored codes and turning off the light.
However, this approach has downsides: it also resets the radio presets, clock, and adaptive learning in the transmission and engine. Use it only if the scanner method isn’t available.
Step 1: Turn Off the Engine and Remove the Key
Safety first:
– Park the car on a flat surface.
– Turn off the engine and remove the key from the ignition.
– Open the hood and locate the battery (usually on the right side of the engine bay).
Step 2: Disconnect the Negative Terminal
The negative terminal (marked with a “-”) is safer to disconnect first to avoid short circuits.
– Use a 10mm wrench or socket to loosen the nut on the negative cable clamp.
– Carefully lift the clamp off the battery terminal.
– Tuck the cable aside so it doesn’t touch the terminal.
Tip: Wear gloves and avoid touching both terminals at once with a metal tool.
Step 3: Wait 15–30 Minutes
Leave the battery disconnected for at least 15 minutes. This allows the ECU’s capacitors to drain, ensuring a full reset.
For a more thorough reset, wait up to 30 minutes.
Step 4: Reconnect the Battery
After waiting:
– Reattach the negative cable to the terminal.
– Tighten the nut securely with the wrench.
– Close the hood.
Step 5: Start the Car and Check the Light
Turn the ignition to “ON” and check the dashboard. The check engine light may flash briefly, then turn off.
Start the engine. If the light stays off, the reset was successful.
Note: You may need to reset the radio, clock, and power windows. The car might also run rough for a few minutes as the ECU relearns driving patterns.
Method 3: Drive Cycle Reset (Passive Method)
In some cases, the check engine light will turn off on its own after the problem is fixed and the car completes a “drive cycle.” This is a series of driving conditions that allow the ECU to retest emissions systems.
This method takes longer but requires no tools.
What Is a Drive Cycle?
A drive cycle for a 1999 Honda Civic typically includes:
– Cold start (engine off for at least 8 hours)
– Idle for 2–3 minutes
– Drive at 30–40 mph for 5 minutes
– Accelerate to 55 mph and cruise for 10 minutes
– Decelerate without braking (coast in gear)
– Repeat 2–3 times
The ECU monitors sensors during this process. If no faults are detected, it clears the codes and turns off the light.
How Long Does It Take?
It may take 3–7 days of normal driving for the light to turn off. If it doesn’t, use the OBD2 scanner or battery method.
Troubleshooting: Why the Light Won’t Reset
Sometimes, the check engine light won’t turn off—even after a reset. Here’s why and what to do:
The Problem Isn’t Fixed
The most common reason the light returns is that the underlying issue wasn’t resolved. For example:
– You tightened the gas cap, but it’s cracked and needs replacement.
– The O2 sensor was cleaned, but it’s still faulty.
Solution: Recheck the repair. Use the OBD2 scanner to see if the same code reappears.
Intermittent Fault
Some issues occur only under certain conditions (like cold weather or high speed). The ECU may not detect them immediately.
Solution: Drive the car through a full drive cycle. If the light stays off for a week, the issue may have been temporary.
Faulty ECU or Wiring
Rarely, the problem is with the ECU or a wiring harness. This requires professional diagnosis.
Solution: Visit a mechanic with advanced diagnostic tools.
Battery Voltage Issues
A weak battery or poor connection can cause the ECU to malfunction.
Solution: Test the battery voltage (should be 12.6V when off, 13.7–14.7V when running). Clean terminals and cables.
Common Mistakes to Avoid
When resetting the check engine light, avoid these pitfalls:
- Resetting without fixing the problem: This is the #1 mistake. Always diagnose and repair first.
- Using the wrong scanner: Ensure your OBD2 scanner is compatible with 1996–2000 vehicles (OBD2 standard).
- Disconnecting the positive terminal first: Always remove the negative terminal to prevent short circuits.
- Not waiting long enough: Rushing the battery disconnect method may not fully reset the ECU.
- Ignoring recurring codes: If the same code returns, the issue is still present.
When to See a Mechanic
While many check engine light issues can be handled at home, some require professional help. Visit a mechanic if:
– The light flashes (indicates a severe misfire that can damage the catalytic converter).
– You’re unable to read or clear the code with a scanner.
– The same code returns after multiple resets.
– You notice performance issues like rough idle, stalling, or poor fuel economy.
A certified technician can perform advanced diagnostics and ensure your 1999 Honda Civic is running safely and efficiently.
Final Tips for Long-Term Maintenance
To prevent future check engine light issues:
– Replace the gas cap if it’s cracked or doesn’t click when tightened.
– Use high-quality fuel and change the fuel filter regularly.
– Replace spark plugs and wires every 30,000–60,000 miles.
– Clean the MAF sensor with specialized cleaner every 15,000 miles.
– Keep up with scheduled maintenance (oil changes, air filter, etc.).
A well-maintained Civic is less likely to trigger the check engine light.
Conclusion
Resetting the check engine light on a 1999 Honda Civic is a straightforward process—if you follow the right steps. The best method is using an OBD2 scanner, which lets you read the code, confirm the repair, and safely clear the light. If you don’t have a scanner, disconnecting the battery works but comes with trade-offs like losing radio settings.
Always remember: the light is there for a reason. Never ignore it or reset it without fixing the problem. With the tips in this guide, you can confidently maintain your Civic and keep that pesky light off for good.