Possible causes

– Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1
– Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 harness is open shorted to ground
– Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit poor electrical connection
– Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit fuse
– Faulty Engine Control Module (ECM)

Tech notes

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. Water getting inside the heated oxygen sensor connector can caused the heated oxygen sensor fuse to blow, which is a very common problem for this type codes. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors.

HO2S Heater Control Circuit Low Bank 1 Sensor 1 is the generic definition for the P0031; however your vehicle’s manufacturer may have a different definition and information for the P0031 code.

When is the code detected?

The P0031 is set when the ECM detects an excessively low voltage through the heated oxygen sensor heater circuit

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0031 Description

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. The faster the heated oxygen sensor reaches that temperature the faster the sensor will start sending an accurate signal to the Engine Control Module (ECM).
In order to achieve the require temperature, a heater element is included inside the heated oxygen sensor. The ECM controls the heated oxygen sensor heater element based on signals from the engine coolant temperature and engine load. The ECM controls the heater element circuit by allowing current flow to ground.
The ECM monitors the voltage signal received through the heater element circuit and determines the state of the circuit by comparing the voltage detected with the factory specifications.

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P0031 Information for specific makes

P0031 AUDI
P0031 BMW
P0031 CHRYSLER
P0031 DODGE
P0031 HYUNDAI
P0031 INFINITI
P0031 INFINITI-2
P0031 JEEP
P0031 KIA
P0031 LEXUS
P0031 MAZDA
P0031 MITSUBISHI
P0031 NISSAN
P0031 NISSAN-2
P0031 SCION
P0031 SUBARU
P0031 SUZUKI
P0031 TOYOTA
P0031 VOLKSWAGEN
P0031 BUICK
P0031 CADILLAC
P0031 CHEVROLET
P0031 GMC
P0031 PONTIAC
P0031 SATURN