P0141 O2 sensor fault code

I just picked up a 96 saturn. The " service engine soon " light came on. So I checked it with my auto xray ez link scanner. The trouble code says " P0141 O2 sensor Heater Circuit Malfunction ( Bank 1 Sensor 2 ) My Haynes Repair Manual says the P0141 fault is "downstream O2 sensor heater or circuit fault" The sensor on the exhaust manifold is about $ 90 and the on on the catalytic converter is about $180. Are there other checks I can do with my scanner to verify which O2 sensor it is? Any help would be appreciated. Thanks