I have a 2002 sienna PO420 front all news sensor back catalytic converte 1 year old engine ligth on po420.

Question

I have the 2 front sensor 1 year old back sensor 10 days old back catalytic converte 1 year old engine ligth on PO420

Answer 1

The 420 code is for the converter right off the exhaust manifold. If the converter down stream was replaced then it is the wrong converter. Also, if you didn't use a factory replacement it is possible the converter is no good. If the engine has had any running issues it can also damage the catalyst. I would check for warranty on the converter, but make sure the correct converter was replaced as well.