Oxygen sensor fault
Oxygen-sensor codes describe the heater or the signal from a sensor before or after the catalyst.
P0135 is a common heater-circuit code on the upstream sensor. P0130 is a circuit or response fault. P0141 is the heater on a downstream sensor.
A sensor code is not automatic proof the sensor is the only failed part. Wiring, exhaust leaks, and mixture faults belong in the same check, which the DTC page outlines.
A trouble code marks a condition to test. It does not by itself prove which part to replace.