P0031
Low SeverityHO2S Heater Control Circuit Low (Bank 1, Sensor 1)
Emissions System
P0031 — Instant Answer
HO2S Heater Control Circuit Low (Bank 1, Sensor 1)
Severity: LOW SEVERITY
Meaning: The O2 sensor heater circuit voltage is lower than expected on the upstream bank 1 sensor. Usually means an open circuit in the heater element.
Safe to drive? Usually yes with caution, but confirm root cause before long trips.
Estimated repair cost: $30 - $100
Most common causes:
- 1. Burned-out O2 sensor heater (35-45% of cases)
- 2. Corroded connector (10-25% of cases)
- 3. Broken wire to O2 sensor (10-25% of cases)
- 4. Blown heater fuse (10-25% of cases)
Symptoms
- ⚠️Check engine light
- ⚠️Poor fuel economy when cold
- ⚠️Higher emissions
- ⚠️Slow O2 sensor response
Related Symptoms
Common Causes
How to Diagnose P0031
- 1Check fuse and relay for O2 heater
- 2Inspect connector for corrosion
- 3Measure heater element resistance
- 4Check for power and ground at sensor
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Related Resources
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Related Symptoms
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Open the exact repair flow most commonly associated with P0031 on this vehicle.
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Related Codes
The oxygen sensor heater circuit on the upstream (pre-cat) sensor of bank 1 has a fault. The heater gets the O2 sensor to operating temperature quickly for proper fuel trim.
The heater in the upstream O2 sensor on bank 1 is not working properly. The heater brings the sensor to operating temperature quickly.
Frequently Asked Questions
- What does P0031 mean?
- P0031 means the upstream O2 sensor heater on bank 1 has low voltage — usually a burned-out heater inside the sensor.
- Is P0031 a cheap fix?
- Yes, O2 sensors cost $30-$100 DIY. It is one of the easier sensor replacements.
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Author & Review
Written by AllOEMManuals Editorial Team. Reviewed by ASE-certified technicians and updated with factory-reference checks for fitment-sensitive steps.
This guide was drafted with AI assistance and reviewed for accuracy by a human editor.
Last updated: 2026-05-07