A high flow shouldn't cause those codes. Especially not the lean code. :thinking:

Now, I'm not very edumacated on the CRV's sensor layout, so are you sure you didn't switch the sensors? (impossible on most B series) Beyond that, are you sure you didn't stretch the wires, let the exhaust hang by the O2, etc?

I wouldn't want to send you off to buy a new ECU or an O2 sim if that's not the problem. The secondary O2 sensor isn't used for fuel feedback and thus it shouldn't even be possible for it to cause a code 45.