Look for high fuel pressure (bad regulator), leaking injector or malfunctioning engine coolant temp sensor. Bank 1 and Bank 2 refer to the cylinder groups on V6 or V8 engines. While the rich mixture may be due to a bad oxygen sensor, there are several specific codes related to the oxygen sensors that may be more likely to show up if the sensor(s) are bad. See volvospeed/bay13 for detailed info on them. These codes distinguish front from rear sensor and refer to them as front HO2S and rear HO2S. How are the performance and fuel economy and is the car hard to start, particularly when engine is already hot?