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General Smog Check

How To Perform a Lexus LS430 Drive Cycle

Hello. I'd like to know how long it'll take to make the emission monitors ready for the smog test. My smog mechanic told me to drive my Lexus for a few days. I've done that but the system is still not complete. The smog machine says monitor not ready.


In most cases, all the emission monitors should run during normal vehicle operation. However, due to different driving habits, the criteria required to run a monitor may not always be met. Following the Lexus LS430 drive cycle below should allow the emission monitors to complete. The drive cycle must be followed accurately. Take extra caution when performing the drive cycle on public roadways. Perform the drive cycle at your own risk. If you feel you might not be able to perform the drive cycle safely, or obey all traffic laws, seek the assistance of a smog check repair station which will be able to perform the drive cycle on a dynamometer and be utilizing specialized OBD II drive cycle readiness tools/scanner/computer.

Your Lexus LS430 must have all of its emission monitors READY or COMPLETE in order to pass the smog test, except for the EVAP monitor (as of the time of this writing). Emission monitors (also known as Readiness Flags) are internal self tests which your Lexus LS430's ECU (engine control unit) conducts to ensure its emission systems are working properly. Typically driving 200-300 miles in both city and highway traffic conditions is sufficient to complete the emission monitors. However at times, a vehicle owners driving patterns do not match those required for the emission monitors to run; and performing the drive cycle's specifics driving pattern is required.

We should begin by noting that certain monitors require the drive cycle start from a cold (engine) start. The air injection monitor is one such monitor. The secondary air injection monitor which checks for the performance of the air injection system and air injection pump is initiated at cold start. Once the engine warms up, the monitor is done checking the air injection pump and will continue on checking the performance of the entire air injection system. With that said, it's not the number of miles driven which resets the air injection monitor, rather the number of cold starts required to get all the other parameters required for the air injection monitor to to run, being met. A cold start is considered starting the engine after the vehicle has sat for at least 8 hours. Since the air injection monitor takes into effect ambient air temperate, it is best to perform a cold start in the mornings.

How to Perform Lexus LS430 Drive Cycle

Begin by: (Make sure you have between 1/4 and 3/4 fuel in the gas tank. The EVAP test will not run while your Lexus has a full tank of gas or the gas tank is near empty). Ensure there are no pending or active trouble codes and that the check engine light is not on. Begin the drive cycle after a Cold Soak. A cold soak basically means, let the vehicle sit overnight. The two important things to remember are... begin when the engine is cold, and make sure you have only 1/4 to 3/4 tank full of gas at all times during the drive cycle.

    A. Start the engine and allow it to idle for 2 minutes or more.

    B. Drive the vehicle at 40-70 mph or more for at least 3 minutes. Be sure to maintain engine speed between 900 and 3,200 rpm.

    C. Stop the vehicle and allow the engine to idle for 10 seconds or more.

    D. Drive the vehicle at 25 mph for at least 40 seconds or more. Be sure to maintain engine speed above 900 rpm.

    E. Stop the vehicle and allow the engine to idle for 10 seconds or more.

    F. Perform steps “D” and “E” ten times.

    G. Drive the vehicle allowing speed to fluctuate between 35-45 mph for about 16 minutes.

If readiness status of all monitors do not switch to “complete,” ensure preconditions are met, turn the ignition switch OFF, then repeat steps “A” through “G.”

Completing the Lexus LS430 drive cycle above should set the emission monitors required to pass the smog check. It will not hurt to perform the drive cycle 2 or 3 times before the smog inspection. Take caution when performing drive cycles on public roadways. If you feel you will be unable to complete the driving pattern above safely, seek assistance from a reputable smog check repair station or Lexus repair facility.

posted by SmogTips Support

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