Hello

My 1987 has three catalytic converters.

There are two in the engine compartment coming off the exhaust manifold (referred to the front cats). These two front cats then feed into a single cat which is often referred to the rear cat.

Do the front two do most of the work and the single rear one is just a "clean up" cat.

Is there a way to test if they are effective?

I have a fluke digital infrared thermometer

What temperatures or temperatures should I see at the input and output of the CATs?

Thanks!