I have a 2005 Sienna minivan with 148,000 miles. Check engine light was on, mechanic said the Oxygen sensors need to be replaced and thermostat too. He changed all of them cost me over $500. But, it does not pass the smog check. I was told at smog check that monitor is not ready and I have to drive around for 100 to 200 miles. Till now, I have driven over 2000 miles, engine light is not on but, monitor still is not ready!!! I have been using good quality gas since I had it fixed. I took it to different smog check all saying ''monitor for cat is not ready!'' I appreciate any feedback to help me what should I do to make the cat monitor ready for smog check?