GMC Repair: check engine light, chev truck, exhaust leaks

Question
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Followup To
Question -
i have a 1998 chev truck with 350 vortec. Check engine light keeps coming on saying bank 1 sensor 2 and bank2 sensor 2 02 sensors have no activity detected or low voltage. I have put new o2 sensors from gm in and still have this problem . I check the wiring harness from the joint by the transmission to the sensors for continuity and there is no breaks in the wire.Im stump Any ideas. Maybe plugged catalytic convertor?
Answer -
Hi,Dustin

Sounds like an O2 sensor heater ckt problem,i would check that first,though you checked the harness,i would see if you are getting good voltage and ground to the sensors check the ENG1 fuse to make sure thats good,then key on and check the ckt539 its a pink wire that should have ign voltage and at battery voltage with it unplugged from the O2's,also check the G105 ground there also its a black wire at the connector,also give me the exact codes that came up.let me know,Thanks

ED
Codes are po140 and po157 thanks dustin

Answer
Dustin

Check the O2 sensor heater ckts i gave you,the pink wire and ground,also make sure there arent any exhaust leaks before the O2's..if there is air induced into the exhaust it'll cause the O2's to run lean,but i think you may have a Heater ckt problem or a bad connection in the heater ckt.

ED