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
OEM Procedures for P0031
HO2S Heater Control Circuit Low (Bank 1 Sensor 1) Found 58 OEM service manual procedures.
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
11 51 000 Removing and installing/replacing the coolant pump (X5 M) - Replacement: Prepare the coolant pump
Showing 8 of 58 procedures
OEM Diagnostic Flowchart
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Parts & Tools for This Job
Common parts shoppers buy for P0031 HO2S Heater Control Circuit Low (Bank 1, Sensor 1).
Oxygen Sensor
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Catalytic Converter
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EVAP Purge Valve
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Gas Cap
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OBD2 scanner
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Check SpecificationsBattery tester
Check cranking and charging health before replacing expensive parts.
A weak battery can mimic alternator or starter problems.
Check SpecificationsMultimeter kit
Confirm voltage, continuity, and sensor power with one simple kit.
A meter is the cheapest way to rule out a bad circuit fast.
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Related Resources
Repair guides, symptom pages, and wiring diagrams related to P0031.
OEM Manual Evidence
Browse →Diagnostic Trouble Codes (DTC) Index — 2013 Audi A3 Premium, 2.0L Eng VIN E, Automatic DCT Trans Service Manual ~ LEMON Manuals LEMON Manua...
Mil On DTC P00AF Stored In ECM Fault Memory (GROUP 01, NO. 12-54) — 2013 Audi A3 Premium, 2.0L Eng VIN E, Automatic DCT Trans Service Manua...
Diagnostic Trouble Codes (DTC) Index — 2013 Audi A3 Premium, 2.0L Eng VIN E, Automatic DCT Trans Service Manual ~ LEMON Manuals LEMON Manua...
Mil On DTC P00AF Stored In ECM Fault Memory (GROUP 01, NO. 12-54) — 2013 Audi A3 Premium, 2.0L Eng VIN E, Automatic DCT Trans Service Manua...
Related Symptoms
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Exact Repair Workflows
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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
Published by AllOEMManuals, founded by Lyndon Bedford, an automotive technician with 20 years of experience. He owned and operated a mechanic shop in Hurst, Texas from 2014 to 2022 and continues hands-on repair work.
Content may combine manual references, general repair templates, and AI-assisted drafting. Confirm the source, vehicle configuration, and applicability before working. Report corrections through our contact page.
Last updated: 2026-10-29