Q: Check engine light on with code P0031.

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The Check Engine light is on with an error code P0031 - Heated Oxygen Sensor (Bank 1, Sensor 1) Heater Circuit Low Code. Severity Level: Moderate, Check and Repair.

Hi. Modern vehicles have heated oxygen sensors or air fuel ratio sensors. The heating element in the sensor brings it up to operating temperature quicker. This allows the powertrain control module (PCM) to use the sensor’s inputs sooner. Code P0031 indicates that there is problem with the heating element or circuit. The bank 1 sensor 1 portion of the code indicates the problem is with the upstream air fuel sensor on the bank 1 side of the engine. A trained technician, such as one from YourMechanic, will be able to diagnose the Check Engine Light and replace any damaged parts.

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