This guide walks you through how to reset the check engine light on a Honda Accord 1999 using simple methods like disconnecting the battery or using an OBD2 scanner. Always diagnose the issue first to avoid recurring problems.
Key Takeaways
- Diagnose the problem first: Use an OBD2 scanner to read trouble codes before resetting the light. Ignoring the root cause may lead to engine damage or repeated warnings.
- Disconnecting the battery works: Turning off the battery for 10–15 minutes can reset the ECU and clear the check engine light on a 1999 Honda Accord.
- Use a code reader for precision: A handheld OBD2 scanner lets you read, understand, and clear codes without guesswork.
- Drive cycle may be needed: After resetting, the car may need a short drive to complete system checks and confirm the issue is resolved.
- Don’t ignore persistent lights: If the light returns, it means the problem still exists and requires professional diagnosis.
- Maintain your Accord regularly: Routine maintenance like replacing spark plugs, oxygen sensors, and air filters prevents many check engine light issues.
- Keep records: Note down codes and repairs for future reference or resale value.
How to Reset Check Engine Light on Honda Accord 1999
If you own a 1999 Honda Accord, you’ve probably seen that little yellow or orange light on your dashboard—the check engine light. It’s easy to panic when it comes on, but don’t worry. This guide will walk you through exactly how to reset the check engine light on a Honda Accord 1999 in a safe, effective, and affordable way.
We’ll cover multiple methods, from the simplest (disconnecting the battery) to the more advanced (using an OBD2 scanner). You’ll also learn why the light comes on, how to interpret trouble codes, and what to do if the light keeps coming back. By the end of this guide, you’ll feel confident handling this common issue like a pro.
Why Does the Check Engine Light Come On?
Visual guide about How to Reset Check Engine Light on Honda Accord 1999
Image source: enginelightfixers.com
Before we jump into resetting the light, it’s important to understand why it’s on in the first place. The check engine light—also known as the malfunction indicator lamp (MIL)—is part of your car’s onboard diagnostic system (OBD2). This system monitors engine performance, emissions, and other critical functions.
When something goes wrong—like a loose gas cap, faulty oxygen sensor, or misfiring spark plug—the system detects an anomaly and triggers the light. The 1999 Honda Accord uses OBD2, which became standard in all vehicles made after 1996. This means your Accord can store trouble codes that help identify the problem.
Ignoring the light can lead to reduced fuel efficiency, increased emissions, or even serious engine damage. So, while resetting the light is easy, diagnosing the root cause is just as important.
Tools You’ll Need
You don’t need to be a mechanic to reset the check engine light on your 1999 Honda Accord. Here’s what you’ll need, depending on the method you choose:
- Basic tools: A wrench or socket set (usually 10mm) to disconnect the battery.
- OBD2 scanner: A handheld code reader (available online or at auto parts stores for $20–$50).
- Safety gear: Gloves and safety glasses (optional but recommended).
- Owner’s manual: For reference on fuse locations and ECU reset procedures.
- Pen and paper: To write down trouble codes before clearing them.
Most of these items are inexpensive and easy to find. If you plan to work on your car regularly, investing in an OBD2 scanner is a smart move.
Method 1: Disconnect the Battery (Simple Reset)
This is the most common and straightforward way to reset the check engine light on a 1999 Honda Accord. It works by cutting power to the engine control unit (ECU), which clears stored trouble codes and resets the system.
Step 1: Turn Off the Engine and Remove the Key
Make sure your car is completely off. Remove the key from the ignition and wait a few minutes for the electrical system to power down. This prevents any accidental shorts or damage.
Step 2: Locate the Battery
Open the hood and find the battery. In the 1999 Honda Accord, it’s located on the driver’s side of the engine bay. It’s a standard 12-volt lead-acid battery, usually black or gray with two terminals.
Step 3: Disconnect the Negative Terminal
Use a 10mm wrench or socket to loosen the nut on the negative terminal (marked with a “-” sign). Always disconnect the negative cable first to avoid sparks. Once loose, carefully pull the cable off the terminal and tuck it away from the battery.
Tip: Wrap the cable end with a cloth or tape to prevent it from touching the terminal accidentally.
Step 4: Wait 10–15 Minutes
This waiting period allows the ECU to fully discharge and reset. Some sources recommend up to 30 minutes, but 10–15 minutes is usually sufficient for a 1999 Accord.
Step 5: Reconnect the Battery
After waiting, reattach the negative cable to the terminal and tighten the nut securely. Make sure it’s snug but don’t overtighten—this can damage the terminal.
Step 6: Turn On the Ignition (Don’t Start the Engine Yet)
Turn the key to the “ON” position (but don’t start the engine). You’ll see the check engine light come on briefly—this is normal. It should turn off after a few seconds if the reset was successful.
Step 7: Start the Engine and Observe
Start the car and let it idle for a minute. If the check engine light stays off, the reset worked. If it comes back on, the problem still exists and needs diagnosis.
Note: Disconnecting the battery may also reset other systems, like the radio presets, clock, and power windows. You may need to reprogram these after the reset.
Method 2: Use an OBD2 Scanner (Recommended)
While disconnecting the battery works, it’s a bit like using a sledgehammer to crack a nut. A better approach is to use an OBD2 scanner. This tool reads the trouble codes stored in your car’s computer, tells you what’s wrong, and lets you clear the codes safely.
Step 1: Locate the OBD2 Port
In the 1999 Honda Accord, the OBD2 port is usually under the dashboard on the driver’s side, near the steering column. It’s a 16-pin connector, often black or gray. You may need to crouch down to see it clearly.
Step 2: Plug in the Scanner
Turn the ignition to the “ON” position (engine off). Plug the OBD2 scanner into the port. Most scanners will power on automatically.
Step 3: Read the Trouble Codes
Follow the scanner’s instructions to read the codes. Common codes for a 1999 Accord include:
- P0420: Catalyst system efficiency below threshold (often a bad catalytic converter).
- P0171: System too lean (could be a vacuum leak or faulty oxygen sensor).
- P0300: Random/multiple cylinder misfire (spark plugs or ignition coils).
- P0440: Evaporative emission control system malfunction (loose gas cap or leak).
Write down the codes before clearing them. This helps you track recurring issues.
Step 4: Clear the Codes
Once you’ve noted the codes, use the scanner’s “Clear Codes” or “Erase DTCs” function. The check engine light should turn off immediately.
Step 5: Turn Off the Scanner and Restart the Car
Unplug the scanner and start the engine. If the light stays off, the reset was successful. If it returns, the underlying issue hasn’t been fixed.
Pro Tip: Some scanners also show live data (like engine temperature, oxygen sensor readings, and fuel trim). This can help you monitor your car’s health over time.
Method 3: Drive Cycle Reset (Natural Clear)
Sometimes, the check engine light turns off on its own after the problem is fixed. This is called a “drive cycle reset.” The ECU runs a series of tests during normal driving and clears the light if no faults are detected.
Step 1: Fix the Underlying Issue
If you’ve replaced a faulty part—like a gas cap, oxygen sensor, or spark plug—the light may go away after a few drive cycles.
Step 2: Drive Normally for 50–100 Miles
Take your Accord on a mix of city and highway driving. The ECU needs to complete several monitoring tests, including:
- Oxygen sensor operation
- Catalytic converter efficiency
- Evaporative emissions system
- Engine misfire detection
Step 3: Check the Light After a Few Days
If the light stays off, the issue is resolved. If it returns, use an OBD2 scanner to check for new codes.
Note: This method doesn’t work if the problem is still present. It only clears the light after the system confirms everything is working properly.
What to Do If the Light Keeps Coming Back
If you’ve reset the check engine light but it keeps returning, don’t ignore it. This means the problem hasn’t been fixed. Here’s what to do:
1. Read the Codes Again
Use your OBD2 scanner to check for new or recurring codes. Compare them to your previous notes.
2. Research the Code
Look up the code online or in your owner’s manual. Many auto parts stores also offer free code reading.
3. Inspect Common Issues
For a 1999 Honda Accord, common causes include:
- Loose or damaged gas cap: Tighten it or replace it if cracked.
- Faulty oxygen sensor: Usually located in the exhaust manifold or downpipe.
- Worn spark plugs or wires: Replace every 30,000–60,000 miles.
- Dirty mass airflow (MAF) sensor: Clean with MAF cleaner spray.
- Vacuum leaks: Check hoses for cracks or disconnections.
4. Seek Professional Help
If you can’t find or fix the issue, take your car to a trusted mechanic. They have advanced diagnostic tools and experience with older Hondas.
Preventing Future Check Engine Light Issues
The best way to avoid check engine light problems is through regular maintenance. Here’s how to keep your 1999 Honda Accord running smoothly:
1. Follow the Maintenance Schedule
Refer to your owner’s manual for recommended service intervals. Key items include:
- Oil and filter changes every 3,000–5,000 miles
- Spark plug replacement every 30,000–60,000 miles
- Air filter replacement every 15,000–30,000 miles
- Fuel filter replacement every 30,000–60,000 miles
2. Use Quality Fuel and Parts
Stick to reputable gas stations and use OEM or high-quality aftermarket parts. Cheap components can fail prematurely and trigger the light.
3. Check the Gas Cap Regularly
A loose or damaged gas cap is one of the most common causes of the check engine light. Make sure it’s tight after every fill-up.
4. Monitor Warning Signs
Pay attention to symptoms like rough idling, poor fuel economy, or hesitation during acceleration. These can indicate early problems.
5. Keep a Maintenance Log
Write down repairs, replacements, and codes. This helps you track patterns and can increase your car’s resale value.
Common Myths About Resetting the Check Engine Light
There are many misconceptions about resetting the check engine light. Let’s clear them up:
Myth 1: Resetting the Light Fixes the Problem
Fact: Resetting only clears the warning. It doesn’t repair the underlying issue. If the problem persists, the light will return.
Myth 2: You Need a Mechanic to Reset the Light
Fact: Anyone can reset the light using a battery disconnect or OBD2 scanner. No special training is required.
Myth 3: The Light Will Never Go Away on Its Own
Fact: If the issue is temporary (like a loose gas cap), the light may turn off after a few drive cycles.
Myth 4: All OBD2 Scanners Are the Same
Fact: Basic scanners only read and clear codes. Advanced models offer live data, graphing, and code definitions. Choose one that fits your needs.
Conclusion
Resetting the check engine light on a 1999 Honda Accord is a simple task that you can do at home with basic tools. Whether you disconnect the battery, use an OBD2 scanner, or let the car reset naturally, the key is to diagnose the problem first. Ignoring the root cause can lead to bigger, costlier repairs down the road.
Remember, the check engine light is your car’s way of saying, “Hey, something’s not right.” Treat it seriously, but don’t panic. With the right tools and knowledge, you can keep your Accord running smoothly for years to come.
Take the time to maintain your vehicle, read trouble codes, and address issues promptly. Your car—and your wallet—will thank you.