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Accord Check engine light

I have a 1998 Accord and had the catalytic converter replaced 4 months ago when the check engine light came on. The check engine light still comes on with a “catalyst system efficiency below threshold” message. The same garage now tells me that they will have to check the oxygen valves. Is this valid and how much should this cost me?

Yes, the oxygen sensors should be scanned to determine if they are telling the truth, or, if one (or, both) is defective.

Thanks. How much time does it take to check the oxygen valves?

Not long, the whole thing should be done in an hour. I’m guessing this car has over 100k miles on it?

No, the car has 88,000 miles on it. It’s a 4 cylinder stick shift. If it’s the oxygen sensors, how much do they cost? I was charged 600 for the catalytic-converter and I’m loathe to shell out again. Was the 600 excessive? It was an after market converter.

The oxygen sensors (NOT oxygen valves) indicate if the catalytic converter is healthy, or not. The oxygen sensors have to be checked to see if they are sick, or healthy. If they are sick, they could be mistaken about the health of the catalytic converter. If they are sick, they are to be replaced.

Here is an article, by the company that makes that tester (scan tool), which is a good write-up about these conditions: