Was the old O2 that came off a Bosch sensor and did you replace it with the identical one? There used to be a problem in the past that they didn't like anything other than OEM. When the 97 went out years back 80K miles ago I was able to get the OEM Bosch sensor at Autozone.http://www.obd-codes.com/p0130
OBD-II Trouble Code Technical Description
02 Sensor Circuit Malfunction (Bank I Sensor 1)
What does that mean?
The O2 sensor produces a voltage based on oxygen content in the exhaust. The voltage varies between .1 and .9 Volts, .1 indicating lean and .9 indicating rich.
The ECM constantly monitors this voltage while in closed loop to determine how much fuel to inject. If the ECM determines that the O2 sensor voltage was too low (less than .4 Volts) for too long (for more than 20 seconds (time varies with model)), this code is set.
Depending if the problem is intermittent or not, there may be no symptoms other than MIL (malfunction indicator lamp) illumination. If the problem is constant, then symptoms may include one or more of the following:
•Engine runs rough, missing or stumbling
•Blows black smoke from tail pipe
• Poor fuel economy