Getting your Lexus HS250h ready for an emissions test or ensuring your car is running optimally after a Check Engine Light (CEL) reset often requires performing an OBDII drive cycle. This process allows your vehicle’s On-Board Diagnostic system to run self-tests and confirm that all emission systems are functioning correctly. If you’ve recently cleared a CEL or disconnected your battery, understanding and executing the correct drive cycle is crucial. This guide provides a detailed, step-by-step approach to completing an OBDII drive cycle specifically for your Lexus HS250h.
Understanding OBDII Drive Cycles for Your Lexus HS250h
An OBDII drive cycle is a series of specific driving conditions that your Lexus HS250h needs to experience to complete its self-diagnostic tests, also known as “readiness monitors.” These monitors assess various emission control systems, such as the oxygen sensors, catalytic converter, evaporative emissions system, and EGR system. When these monitors are in a “ready” state, it signifies that these systems have been tested and are operating as expected. If the monitors are not ready, your vehicle might fail an emissions test, and you may still experience performance issues.
The following procedures outline the specific driving patterns required to set each monitor to a “ready” status on your Lexus HS250h. Ensure you follow these steps carefully and safely, preferably in an area with minimal traffic. It’s also recommended to use an OBDII scan tool to monitor the readiness status of each system in real-time, making the process more efficient.
Lexus HS250h OBDII Drive Cycle Procedures
Here are the individual drive cycle procedures for each emission monitor on your Lexus HS250h. It’s important to note the preconditions for each monitor to ensure the drive cycle can be completed successfully.
EGR Monitor Drive Cycle
Preconditions:
- MIL (Malfunction Indicator Lamp – Check Engine Light) must be off.
- Altitude must be below 7801 feet.
- Intake Air Temperature (IAT) must be above 13°F (-10°C).
Driving Procedure:
- Connect an OBDII scan tool to your Lexus HS250h to observe the data stream and monitor the status of the EGR monitor.
- If the Intake Air Temperature (IAT) is less than 50°F (10°C) at engine start-up, idle the engine for 10 minutes.
- Drive your Lexus HS250h at a steady speed between 43 & 56 mph (69 – 90 km/h) for three to five minutes. Maintain smooth throttle inputs, avoid sudden accelerations, and do not exceed 30% Throttle Position Sensor (TPS).
O2 Sensor Heater Monitor Drive Cycle
Preconditions:
- MIL must be off.
Driving Procedure:
- Start the engine of your Lexus HS250h and allow it to idle for 9 minutes.
- Drive the vehicle at 25 mph (40 km/h) or more for at least 2 minutes.
Evaporative Monitors Drive Cycle
Preconditions:
- MIL must be off.
- Fuel level must be between 1/2 and 3/4 full.
- Altitude must be below 7801 feet.
- Engine Coolant Temperature (ECT) & IAT must be between 40-95°F (4-35°C).
Cold Soak Procedure:
- Start the engine and allow the Engine Coolant Temperature (ECT) to reach 176°F (80°C) or higher, either by idling or driving.
- Let your Lexus HS250h sit for 8 hours, or until the difference between IAT and ECT is less than 13°F (7°C).
Driving Procedure:
- Connect an OBDII scan tool to observe data stream and monitor status of the Evaporative monitor.
- Release pressure in the fuel tank by removing and re-installing the fuel cap before start-up.
- Smoothly drive your Lexus HS250h for 15 minutes at 45 mph (72 km/h).
- Check monitor status using the scan tool.
- If the monitor has not set, smoothly drive the vehicle for 15 minutes at 25 mph (40 km/h).
- Include two stops of 30 seconds during the 15-minute period at 45 mph.
Catalyst Monitor Drive Cycle
Preconditions:
- MIL must be off.
- Engine Coolant Temperature (ECT) must be 176°F (80°C) or more.
- Intake Air Temperature (IAT) must be 14°F (-10°C) or more.
Driving Procedure:
- Connect an OBDII scan tool to observe the data stream and monitor the status of the Catalyst monitor.
- Note the IAT data for use in step 3.
- Drive your Lexus HS250h at a steady speed between 40-55 mph (64-88 km/h) or more for:
- 7 minutes if IAT was below 50°F (10°C) at start-up.
- 3 minutes if IAT was above 50°F (10°C) at start-up.
- Drive the vehicle at 35-45 mph (56-72 km/h) for 7 minutes.
O2 Sensor Monitors Drive Cycle
Preconditions:
- MIL must be off.
Driving Procedure:
- Connect an OBDII scan tool to observe data stream and monitor the status of the O2 Sensor monitors.
- Start the engine and allow it to idle for at least 2 minutes.
- Drive your Lexus HS250h at 25 mph (40 km/h) or more for at least 50 seconds; maintain engine speed above 900 rpm.
- Stop the vehicle and idle the engine for at least 40 seconds.
- Repeat steps 3 & 4 until the monitor sets or a maximum of 10 times.
Full Lexus HS250h OBDII Drive Cycle Checklist
To simplify the process, here’s a combined driving procedure checklist incorporating all the necessary steps for a complete OBDII drive cycle on your Lexus HS250h.
Preconditions:
- MIL must be off.
- Fuel tank is 1/2 to 3/4 full.
- Allow engine coolant temperature to warm up to 176°F (80°C) (achieve this through normal driving, like a commute).
- Let your Lexus HS250h sit for 8 hours or more (cold soak).
Driving Procedure:
(During driving, maintain smooth throttle input, avoid sudden acceleration, and do not exceed 30% TPS)
- Remove and reinstall the fuel cap to release fuel tank pressure.
- Start the engine and idle for 10 minutes.
- Drive at approximately 45 mph (72 km/h) for 15 minutes, including two stops of 30 seconds each during this period.
- Repeat the following sequence up to 10 times, or until all systems are ready:
- Drive at speeds greater than 25 mph (40 km/h) for at least 1 minute.
- Stop the vehicle and idle for 1 minute.
By following these procedures, you should successfully complete an OBDII drive cycle for your Lexus HS250h and ensure all emission monitors are in a “ready” state. Utilizing an OBDII scan tool throughout this process will provide real-time feedback and confirm when each monitor has successfully completed its test. This ensures your vehicle is ready for emissions testing and operating at its optimal performance.
