P0155
Low SeverityO2 Sensor Heater Circuit (Bank 2, Sensor 1)
Emissions System
P0155 — Instant Answer
O2 Sensor Heater Circuit (Bank 2, Sensor 1)
Severity: LOW SEVERITY
Meaning: Heater failure in the upstream O2 sensor on bank 2.
Safe to drive? Usually yes with caution, but confirm root cause before long trips.
Estimated repair cost: $30 - $100
Most common causes:
- 1. Failed heater element (35-45% of cases)
- 2. Blown fuse (10-25% of cases)
- 3. Wiring issue (10-25% of cases)
Symptoms
- ⚠️Check engine light
- ⚠️Slightly worse fuel economy cold
- ⚠️Failed emissions
Related Symptoms
Common Causes
How to Diagnose P0155
- 1Check O2 heater fuse
- 2Measure heater resistance
- 3Inspect wiring
- 4Replace sensor
OEM Procedures for P0155
O2 Sensor Heater Circuit (Bank 2 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 P0155 O2 Sensor Heater Circuit (Bank 2, 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 P0155.
OEM Manual Evidence
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Related Symptoms
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Related Codes
The heater in the upstream O2 sensor on bank 1 is not working properly. The heater brings the sensor to operating temperature quickly.
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.
Heater failure in downstream O2 sensor bank 2.
Frequently Asked Questions
- Is the bank 2 O2 sensor different from bank 1?
- Often yes — bank 1 and bank 2 upstream sensors may have different part numbers due to wire length or connector style.
- Can I use universal O2 sensors?
- Yes, but you must splice the wires correctly. Direct-fit sensors are easier and more reliable.
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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: 2026-11-06