$01 Readiness Flag Status

MODE $01 also includes the Readiness Flag Status. Readiness flag status means the testing of each flag was completed at least once since the memory was the last reset. This information can be used to verify a repair by running specific monitor test(s) and watching the readiness flag flip to COMPLETE. State emissions inspection programs use it as one requirement to pass or fail the OBD part of the inspection. 

This example shows the Monitors Complete Since DTC Cleared. Once COMPLETE, they can only be reset to Incomplete by performing a MODE $04 diagnostic clear or removing power from or reprogramming the Engine Control Module (ECM). 

If you want to verify a repair, turn off a Malfunction Indicator Lamp (MIL) without resetting the memory. Viewing the readiness flag status Complete for Drive Cycle is an option in this case. This is also called PID $41 Monitors Complete this Drive Cycle. 

At each key-on, all readiness flags will display as Incomplete. When monitor tests required to flip a readiness flag to complete run and pass, the status will be updated to COMPLETE this drive cycle. If any readiness flag remains INCOMPLETE, the monitor test(s) required to flip that flag did not run and/or complete. Note: this open is only available while connected to a CAN-equipped system. 

Once readiness flags are COMPLETE for pre-CAN vehicles the memory must be cleared and the vehicle driven to reset the flags to Complete. 

The following video shows how to check IM Readiness Status. It will show Readiness Flag Status since the last time the memory was cleared. It will also show IM Readiness Status for this drive cycle (PID $41).

https://youtu.be/gecNp9Z7ii0