Generic OBD DTC
Ford P0135: O2 Sensor Heater Circuit (Bank 1, Sensor 1)
Heater circuit fault for bank 1 sensor 1 — distinct from P1000 incomplete readiness.
Moderate — diagnose the related faultO2 sensor heater
What the code tells you
- The PCM detected a heater-circuit concern for B1S1.
What it does not tell you
- That P1000 means an O2 sensor has failed.
Diagnostic direction
- 1
If the heater monitor is incomplete and P0135 is present, diagnose the heater circuit.
- 2
Do not replace O2 sensors solely because P1000 is displayed.
Related codes
Possible causes are listed only when they are this code’s actual meaning — not a generic template pasted onto every DTC.
This site provides general diagnostic information. Vehicle procedures vary by model, year, engine, and calibration. Follow Ford service information and local regulations, and use a qualified technician when diagnosis or repair exceeds your experience.