Ok the cats are under warranty but the CCCU, thermcouple, and "o" senser are out of warranty. The OBDII shows code 1426 which has been there for ever and no other codes. How do I find which thermal couple or CCCU unit is the one that is causing the Slow Down light to trigger once and a while on is the Cat going bad. The car has 42K on it now. The Cats come out of Warranty in a few months.