I got a 26 code off jumper e-1 te-1. I am assuming this is an O2 sensor but I also have a couple of exhaust leaks. Should i start with the exhaust leaks or the O2 sensors.

 

If the exhaust leaks are before the o2 sensor then they will most likely be your problems. The o2 sensor will think the motor is running lean and will richen the mixture up. You can test the o2 sensor with a digital multi-meter.