Picked up a 95 automatic a month or so ago after I wrecked my 98. I'm only planning on keeping it for a little while until I have saved up enough to pick up another 4th gen (too much rust damage, automatic, etc.)

Until I have enough to get another one though I have to keep this one running decently. Starting with when I bought it I pulled a couple codes off, rear O2 0707, knock sensor 0304, and 0504 Automatic Transmission Control Unit Signal to ECU.

I reset the ECU periodically since I have owned the car. The only code I consistently pull is the knock sensor. I have changed this before on my 98 and have one on order so I will be doing this when it gets here.

The 0504 code has never returned. 0707 shows up about 50% of the time and occasionally I pull the code for one of the front O2 sensors (can't remember which one)

So, my question is does the inconsistency of the O2 sensor codes indicate they are merely in the process of failing but aren't totally dead or is the knock sensor being dead causing the O2 sensors to trip when they are still fine?

I was just going to leave the rear O2 sensor as from everything I've read it doesn't hurt mileage. I bought a new front sensor but the code has not occurred in the past couple weeks so I'm not sure if I really need to do it.