1998 Plymouth Grand Voyager P0135 O2 Sensor Fault: Causes, Testing & Solutions

Vehicle: 1998 Plymouth Grand Voyager, 3.3L engine, mileage over 437,000 miles (VIN: 2P4GP44R2WR686191) I recently replaced the oxygen sensor for a vehicle inspection. I installed a Bosch O2 sensor model 13122 on Friday night and used my friend's Mac TaskPlus device to monitor OBD-II codes. After driving approximately 130 miles, the system cleared the P0135 code. However, by Monday morning, after driving over 60 miles, the P0135 fault code reappeared. I drove another 30 miles and managed to clear the code again. The issue returned after a further 60-mile drive, and upon resetting the system twice (after about 35 miles), the P0130 code came back. I’ve read that O2 sensor performance may be affected at high mileage, but in my case, no noticeable drivability issues were observed—no loss of power or poor fuel economy. My understanding is that the oxygen sensor heater should activate shortly after engine startup, once the engine reaches operating temperature. Is this correct? The new O2 sensor has two white wires, one black, and one gray wire. What do these wires represent? For an ohm test, which wires should I measure between? I used a Fluke multimeter to test previous used O2 sensors—measured 0.005 and 0.007 ohms on the two white wires. The new Bosch sensor reads 0.003 ohms. I’ve also read that OEM sensors are recommended for reliability, especially in older vehicles like mine. Is this advice valid? If you have more detailed testing procedures or insights into P0135 behavior in a 1998 Grand Voyager, I’d greatly appreciate the clarification. Thank you! Steve