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

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2008 Mercury Sable, 2008 Mercury Mountaineer, 2008 Mercury Milan, 2008 Mercury Mariner, and 2008 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.
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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