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

2009 Ford Fusion SEL, 3.0 1, FWDSECTION DTC P0135: - O2 Heater Circuit (Bank 1, Sensor 1)
DTC 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 poor mating terminals and wiring
  • 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 
E-Series 4.6L,
E-Series 5.4L,
Expedition,
F-150,
Flex,
MKS,
Navigator,
Sable PZEV,
Taurus PZEV,
Taurus X
PZEV
GO to Pinpoint Test DZ .
All others GO to Pinpoint Test DW .
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.