Q: Q: Is my Catalytic Converter bad?

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Last week the sharp rattling noises began. Mechanic diagnosed bad Cats...

Waiting for weld shop to get new cats in and didn't drive the car. Today I drove to work and there was zero noises...

Taking car to shop tomorrow but need to know if this is normal for the rattling to just stop...

Btw, performance seems normal during all the noise/no noise the past six days...

My car has 49000 miles.
My car has a manual transmission.

Hello - yes, it is possible that catalytic converter is busted. This ceramic honeycomb is fragile, and a good whack on the converter from a good size stone, or a speed bump that was a bit too high, can easily break the honeycomb from impact on the case. The pieces can become hot enough to "glue" themselves back together - temporarily, but since the honeycomb is directional (exhaust gases flow through them -- over a platinum catalyst), the odds of them aligning correctly are similar to winning the lottery. You are doing the right thing by replacing them.

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