Your P0041 code is non-sensical because the 4 cylinder Focus only has a single bank of cylinders (V6s and V8s have two). It may be indicative of a wiring harness short. The only way to tell is to do a visual inspection of the downstream O2 sensor connectors and wires.
If the speedo sometimes quits as well it would be suggesting you have an electrical short somewhere.
If the DTC codes reappear, the problem is persistent. Your method of clearing the codes is correct, although using a proper OBDII code scanning device would be better.