2006 Lexus GS 300 Owners Manual - Page 1151

MAINTENANCE EMISSION INSPECTION AND MAINTENANCE (I/M) PROGRAMS Some states have vehicle emission inspection programs which include OBD (On−Board Diagnostics) checks. The OBD system monitors the operation of the emission control system. When the OBD system determines that a problem exists somewhere in the emission control system, the malfunction indicator lamp comes on. In this case, your vehicle may not pass the I/M test and need to be repaired. Contact your Lexus dealer to service the vehicle. Even if the malfunction indicator lamp does not come on, your vehicle may not pass the I/M test as readiness codes have not been set in the OBD system. Readiness codes are automatically set during ordinary driving. However, when the battery is disconnected or run down, the codes are erased. Also, depending on your driving habits, the codes may not be completely set. Also, if the malfunction indicator lamp had come on recently due to temporary malfunction such as a loose fuel tank cap, your vehicle may not pass the I/M test. The malfunction indicator lamp will go off after taking several driving trips, but the error code in the OBD system will not be cleared unless about 40 trips or more are taken. If your vehicle does not pass the I/M test and the malfunction indicator lamp does not come on, contact your Lexus dealer to prepare the vehicle for re−testing. 505