My 1998 Toyota Avalon check engine light is on! Help!

Better off having professional scan test - parts stores can’t even come close! They can only read codes - that’s a far cry from a real scan test. Do not waste money and time replacing parts based solely on trouble codes nor the recommendations of a PARTS SALESPERSON - they love to sell PARTS ! Good luck!

Seafoam... oh boy. I recently had a client who used this that caused all kinds of problems with their vehicle as a result. The moral of the story is: there's no magic solution to vehicle problems, and no mystery oil that is a fix-all.