Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected a problem with the heater in one of the oxygen sensors. It's like a tiny heater that helps the sensor work better, and it's not getting enough power.
Oxygen sensors have heaters to help them reach operating temperature quickly. This code indicates a low voltage in the heater circuit for the oxygen sensor on bank 1, sensor 1.
The P0031 code is triggered when the Engine Control Module (ECM) detects that the heater circuit in the oxygen sensor (located on bank 1, sensor 1) is not operating properly due to low voltage. This heater is essential for the sensor to function correctly, especially during cold starts.
• Check Engine Light illuminated
• Poor fuel economy
• Increased emissions
• Rough idling
• Faulty oxygen sensor
• Blown fuse for the oxygen sensor heater circuit
• Damaged wiring or connectors in the heater circuit
• Faulty Engine Control Module (ECM)
HO2S: Heated Oxygen Sensor
ECM: Engine Control Module
• Use an OBD-II scanner to confirm the code.
• Visually inspect the oxygen sensor and its wiring.
• Check the fuse for the oxygen sensor heater circuit.
• Test the voltage and resistance in the heater circuit.
• Replace the faulty oxygen sensor.
• Repair or replace damaged wiring or connectors.
• Replace the blown fuse.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Socket set
• Wire repair kit
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford F-150
• Regularly inspect and maintain oxygen sensor connections.
• Replace oxygen sensors at recommended intervals.
• Ensure proper function of the vehicle's electrical system.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
• Regular maintenance can prevent such issues.
Oxygen sensors may be covered under emissions warranty. Check with your manufacturer.
P0031 is a common code that often appears in vehicles with aging oxygen sensors or electrical issues in the heater circuit.
Moderate – It should be addressed soon to prevent further engine performance issues.
Ignoring this code may lead to increased emissions, which can be illegal in some areas.
• Engine at operating temperature
• Vehicle idling
Bank 1 Sensor 1 is typically located in the exhaust manifold or close to it, on the side of the engine with cylinder 1.
Q: Can I drive with a P0031 code?
A: It's possible to drive, but it is not recommended as it can lead to poor fuel economy and increased emissions.
Q: How do I know if my oxygen sensor is bad?
A: Symptoms include a Check Engine Light, poor fuel economy, and rough idling.
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Fitment Required · Vehicle-fitment part
Relevant when the code or supporting diagnostics point toward upstream or downstream oxygen-sensor faults.
This code family often involves upstream or downstream oxygen-sensor diagnosis.
Verify exact sensor position and vehicle fitment before buying.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.