jeep cherokee codes
 

i plugged in my superchip and used the diagnostics function. it gave me these 3 codes:
1.P0141: o2 sensor 1/2 heater performance
2.P0705: transmission range sensor circuit
3.P1694: no engine bus messages

what do they mean, how serious are they, and what can/should i do about them?

99xj with 97 motor. 4.5" lift, 31" tires, cold air intake, cat-back exhaust, superchip