Getting 2 engine codes; PO134 & PO135. What do these codes mean. on 2004 Chevrolet Tahoe

Getting 2 engine codes; PO134 & PO135. What do these codes mean. And what's the estimate cost to repair?

Asked by for the 2004 Chevrolet Tahoe
2 answers
OX SENSOR HEATER CIRCUIT ISSUES. COULD BE SENSORS OR WIRING ISSUES.SEEK COMPLETE DIAG AS TO NOT WASTE MONEY
Codes are for the heater circuits on 2 separate oxygen sensors. Suspisious that you 2 go at same time. Could be te sensors themselves. But posssible causes are: Oxygen (O2) Sensor Wiring, Oxygen Sensors, or Powertrain Control Module (PCM)
I cannot help you with cost....need to pin down whats wrong first.u