So recently I've been looking for a O2 sensor for my '91 BMW E30 318ic. I recently bought a slew of parts of which one was a 4 Wire O2 Sensor, Alas when it arrived I found my AFM and current O2 Sensor are 5 Wire, and I cannot seem to find a sensor that is compatible. All that I seem to be finding are 4 wires and the few 5 wires i find don't look the same as what I currently have. I don't have any pictures but it looks very similar to the 4 wire but it has one extra plug, same/similar threaded bit that threads onto the side of the AFM. If anyone has any idea where I could find the correct sensor I'd appreciate it.