Kind of. The O2 sensor controls how much fuel is injected into the cylinders, but on the F23A4 there is what Honda calls an 'A/F sensor' on the exhaust manifold that controls the A/F ratio differently and makes sure it is correct for emissions purposes. They're a little different, which is why Honda calls them by different names. But yeah, the terms are generally interchangeable and on everything except the F23A4 it's an O2 sensor. Observe:



In any event, he probably got the CEL because he bought an aftermarket O2 sensor and not the correct Honda A/F sensor.