Well, the thing with Toyotas and Check Engine Lights, is that it can be ignored in some cases up until state emissions. For some reason, the weak spot in Toyota relibility is that the O² sensors tend to fail prematurely or have a lot of problems, and thus, the CEL comes on. There really is no loss in performance or increase in emissions. We and other friends have had Toyotas before and in every case, this is the problem.