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P0135 - O2 Heater Circuit (Bank 1, Sensor 1)

P0135 - O2 HEATER CIRCUIT (BANK 1, SENSOR 1)

Description:  During testing the heated oxygen sensor (HO2S) heaters are checked for open and short circuits and excessive current draw. The test fails when the current draw exceeds a calibrated limit or an open or short circuit is detected.
Possible Causes: 
  • Vacuum hose disconnected on exhaust gas recirculation (EGR) system module (ESM) applications
  • Short to VPWR in the harness or HO2S
  • Water in the harness connector
  • Open VPWR circuit
  • Open UO2SHTR circuit
  • Open GND circuit
  • Low battery voltage
  • Corrosion or incorrect harness connections
  • Damaged HO2S heater
Diagnostic Aids:  Inspect the connectors for signs of damage, water ingress, or corrosion.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
Sable PZEV,
Taurus PZEV,
Taurus X PZEV		   refer to PINPOINT TEST DZ .
All others   refer to PINPOINT TEST DW .
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