Precat Oxygen Sensor

[1998BMWZ3]

Hello Everyone,

I own a 1998 BMW Z3 with 56K miles. Past few days, the CEL was going ON & OFF intermittently so bought the Fault Code Reader and the machine shows one fault code: "0A: Precat oxygen sensor".

I am not sure what that means. Do I need to replace the sensor? Any guesses how much expenses I can expect if I take it to a professional mechanic?

Also, is this a common thing or a symptom of something else being wrong?

Appreciate your inputs!

[Bear]

You may have two O2 sensors, one in the exhaust manifold and one on the catalytic convertor, hence the pre-cat prompt.