how to check to make sure cat. converter is bad
code po420 on 2000 Toyota Corolla
Typically you will have a Check Engine Code P0420 or it will rattle, especially in the morning. The code P0420 is common for the 1.8 lire Corollas. see the link below.
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how can i check to see that the cat converter is not bad?
check back pressure with gauge
I have problem on codep0420
check for p0420 TSB! get toyota to reprogram it. they'll charge ~$100 but cheaper than replacing the Cat.