Hi i have a Nissan 200SX s14 series 2. my car has never had a working o2 sensor since i bought it and mechanics have traced the problem back to my ECU. the man who tuned my car is Trent from Chequered tuning and is the most reputable tuning business in victoria, Australia. he assures me that the O2 sensor has been turned on in the settings on the ecu through the software. the mechanic believes its a setting inside the actual ECU itself so i took some pictures of it so hopefully someone on this forum can help me out! if i havent provided enough information please let me know and ill do my best to get it. thanks for the help!