Toyota Repair: RAV4 engine light and history, scantool, autoparts store

Question
Rav4 2001, Engine light came on, catilic converter needs to be replace. It has 75500 miles on it. I just purchased it two weeks ago. I asked how this could not be caught in the inspection done. Said that history from engine lights is not stored and is cleared out each time the light comes on? Is this true? Should i take it to someone else to see if it has come on before i purchased it? I am fighting with the dealership to have them pay for this, stating that it had a clear history.

Answer
The only way the codes are cleared is if the battery is disconnected or erased using a diagnostic scantool. In order to confirm that the converter is the problem i would need some diagnostic troiuble codes, can you get them for me, any autoparts store like autozone can help you get them at no charge. The seller could have cleared the engine light before selling it to you. It usually takes a few days for the check engine light to turn on again after erasing the code. You can also go to CARFAX.COM and for a small fee get a complete history of any repairs or problems that the car had before it was sold, that may help.