1998 Mazda B4000 DTC P0133: O2 Sensor Bank 1 Sensor 1 Location & Fix Guide

Hi everyone, I've been experiencing recurring check engine light issues on my 1998 Mazda B4000, with the fault code consistently showing as P0133 — Oxygen Sensor Bank 1, Sensor 1: Slow Response. My mechanic previously diagnosed and cleaned one of the O2 sensors using carb cleaner, which resolved the issue for about 6 to 7 months. However, the problem has returned recently. I'm trying to figure out exactly which O2 sensor corresponds to 'Bank 1, Sensor 1' on my Mazda B4000. The challenge is that most repair manuals I find are based on the Ford Ranger — which shares a similar platform and build location — but there are known differences in sensor wiring and bank numbering. I've heard a common rumor: that on the Ford Ranger, Bank 1 is on the driver's side, while on the Mazda B400 or B4000, Bank 1 may be located on the passenger side. Is this accurate? Could someone confirm whether 'Bank 1, Sensor 1' on a 1998 Mazda B4000 refers to the sensor on the driver's side or passenger side? I can see two O2 sensors — one on each side — and I want to know which one to replace or clean, especially since access is difficult. Any confirmed technical details or reliable sources would be greatly appreciated. Thanks in advance! Rich