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Catalytic Converter

I’m looking at purchasing a 1996 Saab 900S with a 2.0L 4 cylinder engine (not turbo) for $700.00. The seller said that the Saab needed a catalytic converter in order to pass inspection. I looked online and saw the part for roughly $350 and the mechanic quoted me for $798.00. Any advice?

Before you buy it you need to find out what caused converter to fail.
If you replace it it may still fail inspection.

How many miles on the car?
Does it burn oil?

Take the car to an independent shop that can read and compare the upstream and downstream oxygen sensor readings and verify that you really need a converter and not just an oxygen sensor. If they do verify it, then ask them of they’ll put an aftermarket “direct fit” converter in for you.

The first stage of the converter seperates the nitrogen and oxygen (NOx) reducing NOx readings and freeing oxygen to convert CO to CO2 and HC to H2O and CO2, But it does this for onlt the NOx molecules that come in direct contact with the coating (the catalyst) on the honeycomb substrate. The most common cause of cat converter failure is the catalyst getting coated by carbon from an engine either using oil or not running cleanly (rich or misfiring). A good tech can compare the two oxygen sensor signals and tell whether it’s the converter or the sensor. The “Gray” area" is that the upstream sensor can also get coated.