AutoCodes – Generic – P0031

P0031 Code - HO2S Heater Control Circuit Low Bank 1 Sensor 1

Quick Answer

Heated Oxygen Sensors (HO2S) are used for fuel control and post catalyst monitoring. Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1, Heated Oxygen Sensor Bank 1 Sensor 1 harness is open shorted to ground, Heated Oxygen Sensor Bank 1 Sensor 1 circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0031 indicates HO2S Heater Control Circuit Low Bank 1 Sensor 1.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1, Heated Oxygen Sensor Bank 1 Sensor 1 harness is open shorted to ground, Heated Oxygen Sensor Bank 1 Sensor 1 circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 102,407

How popular is this code, among other codes? Medium

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 23, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
Comments
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Code P0031 Description

Heated Oxygen Sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach an operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensors to reach operating temperature. Voltage is provided to the heater by an ignition voltage circuit through a fuse. With the engine running, the ground is provided to the heater by the HO2S heater low control circuit through a low side driver within the Engine Control Module (ECM). The ECM uses Pulse Width Modulation (PWM) to control the HO2S heater operation to maintain a specific HO2S operating temperature range.
The Diagnostic Trouble Code (DTC) will be set when the ECM detects a short to ground in the heater output low side driver circuit of the heated oxygen sensor when the heater is commanded OFF for greater than 5 s.

OBDII Code P0031 - HO2S Heater Control Circuit Low Bank 1 Sensor 1 - AutoCodes.com — P0031 Code - HO2S Heater Control Circuit Low Bank 1 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P0031?

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

How to Fix the DTC P0031?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The control module monitors how long it takes the sensor to warm up and start sending an adequate signal. The code is set when the sensor is taking too long to warm up. Water getting inside the heated oxygen sensor connector can cause the heated oxygen sensor fuse to blow. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors. If the fuse and connector are OK, replacing the O2 Sensor usually takes care of the problem.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0031 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific Makes

P0031 Audi — HO2S Heater Control Circuit Low Bank 1 Sensor 1
P0031 BMW — HO2S 11 Heater Control Circuit Low
P0031 Buick — HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 1
P0031 Cadillac — HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 1
P0031 Chevrolet — HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 1
P0031 Chrysler — O2 Sensor 1/1 Heater Circuit Low
P0031 Dodge — O2 Sensor 1/1 Heater Circuit Low
P0031 Ford — HO2S Heater Control Circuit Low Bank 1 Sensor 1
P0031 GMC — HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 1
P0031 Hyundai — HO2S 11 Heater Circuit Low
P0031 Infiniti — HO2S11 Heater Control Circuit Low
P0031 Infiniti — Air Fuel Ratio Sensor 1 Heater Bank 1 Control Circuit Low
P0031 Jeep — O2 Sensor 1/1 Heater Circuit Low
P0031 KIA — HO2S 11 Hater Circuit Low Input
P0031 Land Rover — HO2S Heater Control Circuit Low Bank 1 Sensor 1
P0031 Lexus — Oxygen Air-Fuel Ratio Sensor Heater Control Circuit Low Bank 1 Sensor 1
P0031 Lincoln — HO2S Heater Control Circuit Low Bank 1 Sensor 1
P0031 Mazda — HO2S Heater Control Circuit Low
P0031 Mercedes-Benz — HO2S Heater Control Circuit Low Bank 1 Sensor 1
P0031 Mercury — HO2S Heater Control Circuit Low Bank 1 Sensor 1
P0031 MINI — HO2S 11 Heater Control Circuit Low
P0031 Mitsubishi — Cylinder 1-4 Heated Oxygen Sensor Front Heater Control Circuit Low
P0031 Nissan — HO2S11 Heater Control Circuit Low
P0031 Nissan — Air Fuel Ratio Sensor 1 Heater Bank 1 Control Circuit Low
P0031 Pontiac — HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 1
P0031 Saturn — HO2S Heater Control Circuit Low Voltage Bank 1 Sensor 1
P0031 Scion — Oxygen Air-Fuel Ratio Sensor Heater Control Circuit Low Bank 1 Sensor 1
P0031 Subaru — HO2S11 Heater Control Circuit Low
P0031 Suzuki — HO2S11 Heater Control Circuit Low
P0031 Toyota — Oxygen Air-Fuel Ratio Sensor Heater Control Circuit Low Bank 1 Sensor 1
P0031 Volkswagen — HO2S Heater Control Circuit Low Bank 1 Sensor 1

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.