Toyota Corolla (E120): Purpose of the readiness tests

  • The on–board diagnostic (obd ii) system is designed to monitor the performance of emission–related components and report any detected abnormalities in the form of diagnostic trouble codes (dtcs). Since the various components need to be monitored during different driving conditions, the obd ii system is designed to ran separate monitoring programs called readiness monitors. Many state inspection and maintenance (i/m) programs require that vehicles complete their readiness monitors prior to beginning an emissions test.
  • The current status of the readiness monitors can be seen by using the hand–held tester with version 9.0 Software (or newer), or a generic obd ii scan tool.
  • To view the readiness monitor status using the hand–held tester, select ”monitor status” from the enhanced obd ii menu.
  • A status of ”complete” indicates that the necessary conditions have been met to run the performance tests for the related readiness monitor.
  • The readiness monitor will be reset to ”incomplete” if:
  • ecm has lost power (battery or fuse).
  • Dtcs have been cleared.
  • The conditions for running the readiness monitor have not been met.
  • In the event that any readiness monitor shows ”incomplete,” follow the appropriate readiness monitor drive pattern to change the readiness status to ”complete.”


: strict observance of posted speed limits, traffic laws, and road conditions are required when performing these drive patterns.


: these drive patterns represent the fastest method to satisfy all necessary conditions which allow the specific readiness monitor to complete.

In the event that the drive pattern must be interrupted (possibly due to traffic conditions or other factors) the drive pattern can be resumed, and in most cases, the readiness monitor will still set to complete.

To ensure rapid completion of readiness monitors, avoid sudden changes in vehicle load and speed (driving up and down hills and/or sudden acceleration).

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