Ensuring your Honda Odyssey passes its emissions test is crucial, and sometimes, you might encounter a situation where the OBDII readiness monitors are not set. These monitors are essential self-checks your vehicle’s computer performs on its emission control systems. If they are not “ready,” your vehicle might fail a smog check, even if there are no underlying issues. A specific driving pattern, known as a drive cycle, can help complete these monitors. This guide provides a step-by-step approach to performing a Honda Odyssey drive cycle, ensuring your vehicle is ready for its emissions test.
The Honda Odyssey Drive Cycle Procedure
This procedure outlines how to perform a Honda OBDII drive cycle specifically for your Honda Odyssey. Remember to always obey traffic laws and perform acceleration steps only where it is safe and legal, such as on highways.
1. Cold Start:
- Begin with a cold start. This means your Honda Odyssey should have been turned off for at least one hour, allowing the engine to cool down completely.
- Ensure your fuel tank is between 1/4 and 3/4 full.
- Verify that the engine coolant temperature is below 122°F (50°C) and within 11°F (6°C) of the ambient air temperature. This cold start is crucial for initiating the diagnostic tests.
- Do not turn the ignition key to the “ON” position before starting the engine, as this might prevent the heated oxygen sensor diagnostic from running correctly.
2. Idle Time:
- Start your Honda Odyssey’s engine and let it idle for 2.5 minutes. It’s important not to drive the vehicle during this phase.
- Turn on the air conditioner and the rear defroster. This idle period allows the Engine Control Unit (ECU), sometimes referred to in broader terms as an Attitude Monitor Obdii system for vehicle condition assessment, to run several self-tests. These include:
- Oxygen Sensor Heater self-test
- Air Injection System Passive Air test
- EVAP Purge “No Flow” test
- Misfire Detection
3. Accelerate (First Acceleration):
- Turn off the air conditioner and rear defroster.
- Begin driving and, as soon as safely possible, apply approximately half throttle until you reach a speed of 55 mph (88 km/h).
- During this acceleration, the ECU continues its diagnostics, focusing on:
- Misfire Detection
- Fuel Trim
- EVAP Purge Flow
4. Hold Steady (First Steady Speed):
- Maintain a constant speed of 55 mph (88 km/h) for three minutes.
- During this steady driving phase, the ECU performs tests on:
- Oxygen Sensor (O2) response
- Air Injection System (AIS)
- EGR Flow
- Purge Valve
- Misfire Detection
- Fuel Trim
5. Decelerate (First Deceleration):
- Slowly release the accelerator pedal, allowing your Honda Odyssey to coast down to 20 mph (32 km/h).
- Crucially, do not use the brakes or shift gears to slow down. The deceleration should be gradual and natural.
- This step allows the ECU to further test:
- EGR System
- EVAP Purge System
- Long Term Fuel Trims
6. Accelerate (Second Acceleration):
- Accelerate again, this time applying about 3/4 throttle until you reach 55-60 mph (88-96 km/h).
- This acceleration phase repeats the same self-tests performed during the first acceleration step, ensuring thorough evaluation.
7. Hold Steady (Second Steady Speed):
- Maintain a steady speed of 55 mph (88 km/h) for five minutes.
- In addition to the self-tests from the first steady speed phase, this longer period allows the ECU to perform the critical catalyst monitor diagnostics.
- If the catalytic converter is nearing the end of its life or if the battery has recently been disconnected, it might take multiple complete drive cycles (up to 5) for the catalyst monitor to complete. Completing the Catalyst Monitor is often the final hurdle in achieving OBDII readiness.
8. Decelerate (Second Deceleration):
- Perform a second deceleration, identical to the first. Slowly release the accelerator and coast down to 20 mph (32 km/h) without using brakes or shifting gears.
- This deceleration again tests the:
- EGR System
- EVAP Purge System
- Long Term Fuel Trims
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This completes one Honda Odyssey drive cycle.
Verifying Monitor Completion
To confirm whether all OBDII monitors are complete, it is highly recommended to use an OBDII scan tool. Connect the scan tool to your Honda Odyssey’s OBDII port and check the status of the readiness monitors. If some monitors are still incomplete, you may need to repeat the drive cycle 2-3 times.
By carefully following these steps, you can effectively perform a Honda Odyssey drive cycle and increase the likelihood of completing your vehicle’s OBDII readiness monitors, paving the way for a successful emissions test. Remember to always prioritize safety and obey all traffic laws while performing this procedure.
