I would like to answer me in a serious problem i have with my car (Toyota Corolla 2003 1.6 sol).
The Check Engine Light in my car illuminates and stays on, and there are not performance problems until now . I immendiately came to the proffesional technician of TOYOTA SERVICES and they told that my car appears the Diagnostic Trouble Code "P0420" Catalyst System Efficiency Below Threshold (Bank 1) and they reset the alarm and they told me that I must replace the three-way catalytic converter to solve the problem.
I do a quik research on Internet and I find that with this trouble code maybe is not so simply just to replace the catalytic.For this reason i ask to us to give me if there is an more specific technical and simply answer to solve my problem.
Thank you in advance,
Diagnostic Trouble Code "P0420" on 2003 Toyota Corolla
This is RepairPal's very detailed discussion of this trouble code and the common resolution. It is very likely that you need a catalytic converter. Hope this helps.