High CO is caused due to a rich fuel mixture. Things to look into are fuel control sensors such as the oxygen sensor, engine coolant temp sensor, and most importantly the mass air flow sensor. A smog technician can measure the voltage output of each of these components the ensure they are operating properly.
If these components check out ok we'd recommend looking into the EVAP system to ensure the EVAP canister is not saturated and/or the EVAP soleniod stuck open.
Mark - SmogTips Support
posted by SmogTips Support
