Sienna System Readiness Check Incomplete

I had something similar happen after running diagnostics. Those readiness monitors can be finicky. Try performing a drive cycle; there are specific procedures for Toyotas involving acceleration and deceleration. If that doesn't work, it might clear itself after normal driving, as long as the underlying issue that triggered the initial diagnostic isn't still present. Has it been through vehicle inspection recently?

Could you elaborate on the 'drive cycle' procedure? I'm not familiar with the specifics, and I want to do it correctly to resolve the incomplete system readiness check. Is there a particular iteration or duration recommended for the Toyota Sienna, to ensure all parameters are adequately tested?

Finding the exact Toyota drive cycle procedure online can be a pain. The point is to get all the emissions systems to run their self-tests. If it won't clear after a normal few days of driving, I'd suggest a visit to a workshop, just to be sure. They'll know the exact Toyota-approved procedure.

Your guidance helped resolve the issue. I kept driving consistently, and the error message cleared. The system readiness check is now complete. The repair cost was 0€, as the problem resolved itself. Thanks again.