Toyota Sienna Service Manual: Purpose of readiness tests

• The On-Board Diagnostic (OBD II) system is designed to monitor the performance of emissionrelated components, and indicate any detected abnormalities with DTCs (Diagnostic Trouble Codes).

  Since various components need to be monitored in different driving conditions, the OBD II system is designed to run separate monitoring programs called Readiness Monitors.

• The intelligent tester's software must be version 9.0 or newer to view the Readiness Monitor status. To view the status, select the following menu items: DIAGNOSIS / ENHANCED OBD II / MONITOR INFO / MONITOR STATUS.
• When the Readiness Monitor status reads COMPL (complete), the necessary conditions have been met for running the performance tests for that Readiness Monitor.
• A generic OBD II scan tool can also be used to view the Readiness Monitor status.

HINT:

Many Inspection and Maintenance (I/M) programs require a vehicle's Readiness Monitor status to show COMPL before beginning emission tests.

The Readiness Monitor will be reset to INCMPL (incomplete) if:

• The ECM has lost battery power or broken a fuse.
• DTCs have been cleared.
• The conditions for running the Readiness Monitor have not been met.

If the Readiness Monitor status shows INCMPL, follow the appropriate Readiness Monitor Drive Pattern to change the status to COMPL.