P0135

What it means

This means the heater inside the oxygen sensor located before the catalytic converter on Bank 1 isn't working, preventing the sensor from reaching its operating temperature quickly.

Is it safe to drive?

While generally safe to drive, a faulty O2 sensor heater means the sensor takes longer to provide accurate readings, leading to reduced fuel economy and increased emissions. It should be addressed to prevent catalytic converter damage.

Most likely causes

• Faulty O2 sensor (heater element failure)

  high

  The heater element within the O2 sensor is a common failure point due to heat cycles.

• Wiring or connector issues to the O2 sensor

  medium

  Damaged, corroded, or loose wires/connectors can interrupt the heater circuit.

• Blown fuse for the O2 sensor heater circuit

  low

  A blown fuse will cut power to the heater, though this is less common for individual O2 sensors.

• Faulty PCM (rare)

  low

  In very rare cases, the PCM itself may fail to provide power to the heater circuit.

Related help

• Full P0135 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?