I have been working on getting my emissions test and the SES light is on. So I had the codes read. One was no activity on bank 2 sensor 1. So I switched the o2 sensor to the left side and had it checked again. That time it was bank 1 sensor 1 too lean. So I bought two new ones and out them in. Had the code reset and drove it around. The light came back on and now it's both front sensors. Does the computer have to have some time to reset?