Correct, disconnect your battery and install some new oxygen sensors and reconnect your battery.i recently got a 90 lx and got it running. it had one O2 sensor and it was damaged pretty bad. i took it out and have drove the car a few times and it has a real rich smell in the call. i figure it is from the sensor holes i have not sealed. so question is the car will run much better with both O2 sensors connected right?