Passing an OBD2 inspection is crucial for Honda owners, especially those with turbocharged engines or other technical modifications. If your Honda fails to pass the smog test due to “readiness monitors not ready,” you’re not alone. This situation often arises after battery disconnection or recent car repairs. Fortunately, there’s a solution: the OBD-II drive cycle. This procedure allows your Honda’s onboard diagnostic system to run self-tests and set the necessary readiness monitors, ensuring you can successfully pass your inspection.
The OBD-II drive cycle is a specific sequence of driving conditions that prompts your car’s computer to check various emission control systems. For Honda vehicles, including turbocharged models, following this cycle can effectively reset the monitors. The drive cycle begins with a cold start. This means the engine coolant temperature must be below 122 degrees Fahrenheit (50 degrees Celsius) and close to the ambient air temperature (within 11 degrees Fahrenheit or 6 degrees Celsius). It’s important to ensure the ignition key is not turned on before this cold start, as it can interfere with the heated oxygen sensor diagnostic.
Here’s a step-by-step guide to perform the OBD-II drive cycle on your Honda:
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Cold Start and Initial Idle: Start your Honda engine when it is cold. Immediately after starting, let the engine idle in drive for two and a half minutes. During this phase, turn on the air conditioning (A/C) and rear defroster. This step allows the OBD-II system to check the oxygen sensor heater circuits, air pump, and EVAP purge system.
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Warm-up and Acceleration: Turn off the A/C and rear defroster. Accelerate smoothly to 55 mph (88 km/h) using about half throttle. This stage initiates checks for ignition misfire, fuel trim, and canister purge.
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Steady Speed Cruising: Maintain a constant speed of 55 mph (88 km/h) for three minutes. During this steady cruise, the OBD-II system monitors the EGR system, air pump, oxygen sensors, and canister purge system.
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Deceleration Phase: Without braking or depressing the clutch, let your Honda decelerate (coast down) to 20 mph (32 km/h). This allows the system to check the EGR and purge functions during deceleration.
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Re-acceleration and Continued Cruise: Accelerate again to 55 to 60 mph (88-96 km/h) at half throttle. This re-checks for misfire, fuel trim, and purge system operation.
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Extended Steady Speed Monitoring: Hold a steady speed between 55 to 60 mph (88-96 km/h) for five minutes. In this phase, the OBD-II system focuses on monitoring catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors, and purge functions over an extended period.
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Final Deceleration and Stop: Finally, decelerate and come to a complete stop without using the brakes. This allows the OBD-II system to perform a final check of the EGR and canister purge systems as the vehicle comes to rest.
After completing this OBD-II drive cycle, your Honda’s readiness monitors should be set, provided there are no underlying issues with your vehicle’s emission control systems. You can then proceed to your OBD2 inspection. Keep in mind that sometimes it may take more than one drive cycle to set all monitors. If you are still experiencing issues, it’s advisable to consult a qualified mechanic to diagnose any potential problems with your Honda’s emission system. This guide is designed to help Honda owners, including those with turbo models and technical modifications, navigate the OBD2 inspection process more effectively.
