Question

What is code P0031​?

The P0031 code is defined as “HO2S Heater Control Circuit Low (Bank 1 Sensor 1),” meaning the powertrain control module (PCM) has sensed a low voltage problem in the oxygen sensor heater circuit (HO2S) in Bank 1, Sensor 1.

The oxygen sensor involved in this error code is in Bank 1. This sensor checks the amount of oxygen in the exhaust gas and compares it with the outside air. The data helps the PCM make the required air-fuel ratio changes as both come inside the engine.

The oxygen sensor 1 should be at a particular temperature if it has to make the correct reading. Whenever required, a heater wire located inside the sensor heats up its temperature. The PCM logs code P0031 when it finds out that the heater wire is faulty or the voltage is extremely low.

What are the symptoms of the P0031 code?

These are some common symptoms that you can observe when the code triggers in your car.

• The check engine light illuminates
• Poor fuel economy
• Decreased engine performance
• The engine runs rough or shows hesitation

What causes a P0031 code?

These are some reasons why the code shows up in your car.

• The O2 sensor is defective
• Issues with the O2 sensor heater circuit
• PCM failure
• Worn heater circuit connectors/wiring
• Incorrect electrical connection

How to fix code P0031

The most common method to fix the error code is by replacing the engine Bank 1 Sensor 1. Also, a mechanic will do the following to fix this engine code.

• The mechanic will verify the code with a scan tool. Reset the error code and do a test drive.
• If the code reappears, follow the test process. Then, the mechanic will ensure that the wiring is good and has the right voltage and ground to the oxygen sensor before replacing the sensor.
• With the engine off and key on, they’ll use a voltmeter to examine for 12+ volts fused battery feed to the heating element. If there is no voltage, do the required repair by replacing any blown fuse.
• If the battery feed is unbroken, they’ll remove the ground circuit from the PCM wiring connector and check for the circuit’s resistance.
• If the resistance is infinite, repair the circuit.
• The O2 sensor will be faulty if the control circuit checks out. Replace it and recheck.

How much does it cost to fix the P0031 code?

Ideally, it will cost anywhere between $150 and $600 to fix engine code P0031. The fix cost can vary greatly depending on the issue, like whether it is a defective upstream oxygen sensor, a PCM failure, or wiring harness damage. Here is a breakdown of the fix costs.

Can I drive with a P0031 code?

No, we don’t recommend you drive your car with engine code P0031, as it points out a problem with the oxygen sensor heater control circuit. Driving with a defective oxygen sensor can lead to your car running with an incorrect fuel mixture, ultimately causing engine damage and poor fuel economy.