Resetting the check engine light on your Honda S2000 doesn’t have to be complicated. This guide walks you through simple methods—from using an OBD2 scanner to a manual battery disconnect—so you can clear the light and confirm your repairs worked. Always diagnose the root cause first to avoid recurring issues.
Key Takeaways
- Diagnose before resetting: Never reset the check engine light without identifying and fixing the underlying issue using an OBD2 scanner.
- Use an OBD2 scanner for accuracy: This is the safest and most reliable method to clear codes and reset the light on your S2000.
- Battery disconnect works—but has risks: Disconnecting the battery can reset the light, but it may also erase radio settings, ECU memory, and trip data.
- Drive cycle matters: After resetting, complete a proper drive cycle to allow the ECU to relearn and verify no new codes appear.
- Check for persistent issues: If the light returns, the problem wasn’t fully resolved—seek professional diagnosis if needed.
- Maintain your S2000 regularly: Prevent future check engine lights with routine maintenance like spark plug changes and air filter replacements.
- Know your model year: 2000–2003 and 2004–2009 S2000s may have slight differences in ECU behavior and reset procedures.
How to Reset Check Engine Light on Honda S2000
If you’ve ever seen that little yellow engine icon flash on your Honda S2000’s dashboard, you know it can be unsettling. The check engine light (CEL) is your car’s way of saying, “Hey, something’s not right.” But once you’ve diagnosed and fixed the problem—whether it’s a loose gas cap, faulty oxygen sensor, or misfiring cylinder—you’ll want to reset that light so you can drive with peace of mind.
Resetting the check engine light on a Honda S2000 isn’t just about aesthetics. It’s about confirming that your repair worked and ensuring your car’s onboard diagnostics system (OBD2) is functioning properly. In this comprehensive guide, we’ll walk you through multiple proven methods to reset the CEL, including using an OBD2 scanner, disconnecting the battery, and even a manual reset trick. We’ll also cover troubleshooting tips, what to do if the light comes back, and how to prevent future issues.
Whether you’re a seasoned S2000 enthusiast or a first-time owner, this guide is designed to be easy to follow, practical, and packed with real-world advice. Let’s get started.
Why the Check Engine Light Comes On
Before we dive into resetting the light, it’s important to understand why it came on in the first place. The check engine light is part of your S2000’s OBD2 system, which monitors engine performance, emissions, and various sensors. When something goes outside normal parameters, the engine control unit (ECU) stores a diagnostic trouble code (DTC) and triggers the CEL.
Common causes include:
– Loose or faulty gas cap
– Oxygen (O2) sensor failure
– Mass airflow (MAF) sensor issues
– Spark plug or ignition coil problems
– Catalytic converter inefficiency
– Exhaust gas recirculation (EGR) valve malfunction
Ignoring the light can lead to reduced fuel efficiency, increased emissions, and even engine damage over time. So, always address the root cause before resetting.
Method 1: Using an OBD2 Scanner (Recommended)
The most reliable and safest way to reset the check engine light on your Honda S2000 is by using an OBD2 scanner. This tool reads the trouble codes, helps you understand the problem, and allows you to clear the codes after repairs.
Step 1: Purchase or Borrow an OBD2 Scanner
You don’t need a professional-grade scanner. A basic OBD2 scanner like the BlueDriver, Innova 3100, or even a budget-friendly Bluetooth model (used with a smartphone app) will work perfectly. These devices plug into the OBD2 port and communicate with your car’s ECU.
Tip: If you don’t want to buy one, many auto parts stores (like AutoZone or O’Reilly) offer free code reading and reset services.
Step 2: Locate the OBD2 Port
In the Honda S2000, the OBD2 port is located under the dashboard on the driver’s side, just below the steering column. It’s a 16-pin connector, usually black or gray, and easy to spot once you know where to look.
Step 3: Turn the Ignition to “ON” (Do Not Start the Engine)
Insert the key and turn it to the “ON” position. This powers up the car’s electrical system and allows the scanner to communicate with the ECU. Do not start the engine unless the scanner specifically instructs you to.
Step 4: Plug in the Scanner and Read Codes
Connect the OBD2 scanner to the port. Follow the device’s instructions to turn it on and initiate a scan. The scanner will retrieve any stored trouble codes (e.g., P0420 for catalytic converter efficiency).
Write down the codes and research them using the scanner’s manual or online resources. This helps confirm what was fixed and ensures no new issues are present.
Step 5: Clear the Codes
Once you’ve confirmed the repairs are complete, use the scanner’s “Clear Codes” or “Reset” function. This erases the stored DTCs and turns off the check engine light.
Important: The light may take a few seconds to go out. If it doesn’t, double-check that the scanner is properly connected and the ignition is on.
Step 6: Verify the Reset
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, there may still be an active issue.
Method 2: Disconnecting the Battery (Manual Reset)
If you don’t have an OBD2 scanner, you can reset the check engine light by disconnecting the car’s battery. This method forces the ECU to reset its memory, including stored trouble codes.
Warning: This method can erase radio presets, ECU adaptive learning, trip computer data, and sometimes even cause the car to run rough for a few miles as the ECU relearns. Use it only if necessary.
Step 1: Turn Off the Engine and Remove the Key
Make sure the car is completely off and the key is out of the ignition.
Step 2: Locate the Battery
The Honda S2000 has a 12V battery located in the trunk, behind the passenger-side panel. Open the trunk, remove the panel, and locate the battery.
Step 3: Disconnect the Negative Terminal
Use a 10mm wrench or socket 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.
Tip: Wear safety glasses and gloves. Battery acid and sparks can be dangerous.
Step 4: Wait 15–30 Minutes
Leave the battery disconnected for at least 15 minutes. This ensures the ECU’s capacitors fully discharge and the system resets completely.
Optional: For a deeper reset, press the brake pedal a few times while the battery is disconnected. This drains residual power from the system.
Step 5: Reconnect the Battery
Reattach the negative terminal and tighten it securely. Reinstall the trunk panel.
Step 6: Turn On the Ignition
Turn the key to “ON” and check if the check engine light is off. If it is, start the engine and let it idle for a few minutes. The ECU will begin relearning fuel trims and sensor data.
Note: The car may run slightly rough at first. This is normal. Drive gently for the first 10–15 miles to allow the ECU to adapt.
Method 3: Drive Cycle Reset (Natural Clear)
Sometimes, the check engine light will turn off on its own after the problem is fixed—especially if it was a minor issue like a loose gas cap. This is called a “drive cycle reset.”
The ECU continuously monitors systems and will clear the light if no faults are detected over several drive cycles.
What Is a Drive Cycle?
A drive cycle is a specific sequence of driving conditions that allows the ECU to test all monitored systems. For the Honda S2000, a typical drive cycle includes:
– Cold start (engine below 122°F)
– Idle for 2–3 minutes
– Drive at varying speeds (25–55 mph) for 5–10 minutes
– Include light acceleration and deceleration
– Highway driving at steady speed (55–65 mph) for 10–15 minutes
– Come to a complete stop and idle again
Complete this cycle 3–5 times over a few days. If the issue is resolved, the CEL should turn off.
Tip: Use an OBD2 scanner to check if monitors are “ready.” All monitors must be ready for the light to stay off.
Troubleshooting: What If the Light Comes Back?
If the check engine light returns after resetting, it means the underlying issue wasn’t fully resolved. Here’s what to do:
Recheck the Original Problem
Go back to the trouble code you originally found. Did you replace the part correctly? Was the repair done to spec? For example, if you replaced an O2 sensor, ensure it’s the correct part number and properly installed.
Inspect Related Components
Sometimes, one faulty part causes another to fail. For instance, a bad spark plug can damage an ignition coil. Check related systems for wear or damage.
Clear Codes and Monitor
Use your OBD2 scanner to clear the codes again, then drive the car normally. Monitor the scanner for new codes. If the same code returns, the problem persists.
Seek Professional Help
If you’ve tried everything and the light keeps coming back, it’s time to visit a trusted Honda specialist or mechanic. They have advanced tools and experience with S2000-specific issues.
Preventing Future Check Engine Lights
The best way to avoid resetting the check engine light is to prevent it from coming on in the first place. Here are some maintenance tips for your Honda S2000:
Regular Maintenance Schedule
Follow the factory-recommended maintenance schedule:
– Change spark plugs every 30,000–60,000 miles (use OEM or high-quality iridium plugs)
– Replace air filter every 15,000–30,000 miles
– Inspect and clean MAF sensor every 30,000 miles
– Check gas cap for cracks or wear—replace if necessary
Use Quality Fuel and Oil
Use premium gasoline (91+ octane) as recommended by Honda. This helps prevent knocking and keeps the engine running smoothly. Also, use synthetic oil and change it every 5,000–7,500 miles.
Inspect Exhaust and Emissions Components
The S2000’s high-revving F20C engine is sensitive to exhaust backpressure and emissions issues. Regularly inspect the catalytic converter, O2 sensors, and EGR system.
Keep the Gas Cap Tight
After every fill-up, make sure the gas cap is tightened until it clicks 3–4 times. A loose cap is one of the most common causes of the CEL.
Model Year Considerations
The Honda S2000 was produced from 2000 to 2009, with a major update in 2004 (AP2 model). While the OBD2 system is similar across all years, there are slight differences:
– 2000–2003 (AP1): Uses the F20C engine with a redline of 9,000 RPM. Slightly different ECU tuning.
– 2004–2009 (AP2): Upgraded to the F22C1 engine with a 8,500 RPM redline and improved low-end torque. Also features a revised intake and exhaust.
Both models use the same OBD2 port location and reset procedures. However, AP2 models may have slightly different monitor readiness requirements.
Final Tips and Best Practices
– Always diagnose before resetting. Never assume the light will go away on its own.
– Keep a log of repairs and reset dates. This helps track recurring issues.
– Invest in a basic OBD2 scanner—it’s a worthwhile tool for any S2000 owner.
– If you’re modifying your S2000 (e.g., headers, ECU tune), be aware that some changes can trigger the CEL. Use a tunable ECU or O2 sensor simulator if needed.
– Don’t ignore the light. Even if the car runs fine, hidden issues can cause long-term damage.
Conclusion
Resetting the check engine light on your Honda S2000 is a straightforward process—but only after you’ve properly diagnosed and fixed the problem. Whether you use an OBD2 scanner, disconnect the battery, or rely on a drive cycle, the key is to ensure the issue is truly resolved.
Remember: The check engine light is your car’s early warning system. Respecting it and responding quickly saves you time, money, and keeps your S2000 running at its best. With the right tools and knowledge, you can confidently maintain your roadster and enjoy every high-revving mile.
Now that you know how to reset the check engine light, you’re one step closer to mastering your Honda S2000. Stay safe, drive smart, and keep that engine singing.