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ENRUDEPLES

P0135 — O2 Sensor Heater Circuit (Bank 1 Sensor 1)

minor

What it means

The ECM measured a current or resistance outside specification in the heating element of the upstream oxygen sensor on bank 1. The heater brings the ceramic element to roughly 300 to 350 degrees Celsius within seconds of starting so that closed loop control can begin early and emissions stay low during warm-up. With a failed heater the sensor only becomes active once exhaust heat warms it, which delays closed loop, raises cold-start emissions and lights the MIL.

Likely causes (most common first)

  1. Open or shorted heating element inside the oxygen sensor
  2. Blown fuse feeding the sensor heater
  3. Corroded connector or broken heater supply wire
  4. Faulty heater control driver or relay in the ECM circuit
  5. Voltage drop from a damaged ground point
  6. Water ingress into the harness connector

Can you drive with it?

You can drive without restriction, but cold-start emissions and consumption stay high until the sensor is replaced.

This is the generic meaning. What about your car?

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