CarFaultIQ

P0155

P0155: O2 Sensor Heater Circuit Bank 2 Sensor 1

Updated Last reviewed December 26, 2026By CarFaultIQ Editorial Team

Verify with official recall databases, service records, a mechanic inspection, and local market data before relying on this summary.

At a glance

Quick diagnostic answer

The heater circuit for the upstream oxygen sensor on bank 2 is drawing or reporting an unexpected electrical condition.

SeverityModerate UrgencyUrgency not yet verified EvidenceSource notes available
OBD code
P0155
System/category
Sensors & Circuits
Severity
Moderate
Structured severity term
Urgency
Urgency not yet verified
Can I drive?
Drive with caution
Usually driveable if the engine runs normally, but do not ignore rough running, poor fuel economy, or multiple fuel-trim codes.
Repair/cost band
$$ · Moderate
Often a moderate sensor or wiring repair; bank and sensor location must be confirmed before parts are ordered.
Vehicle applicability
Generic OBD-II code across many makes and models; confirm service information for the exact vehicle.
Current applicability note is free text

Computed rule output may be more cautious than stored content and is never used to soften safety-critical risks.

Short answer

P0155 usually means the heater circuit for the upstream oxygen sensor on bank 2 is drawing or reporting an unexpected electrical condition. Usually driveable if the engine runs normally, but do not ignore rough running, poor fuel economy, or multiple fuel-trim codes. Confirm bank 2 sensor 1 location, then check the connector, heater fuse feed, and wiring near the exhaust.

SeverityModerateDrive?Drive with cautionRepairProfessional

Key takeaways

  • P0155 points to a detected condition, not an automatic parts order.
  • Usually driveable if the engine runs normally, but do not ignore rough running, poor fuel economy, or multiple fuel-trim codes.
  • Confirm bank 2 sensor 1 location, then check the connector, heater fuse feed, and wiring near the exhaust.
  • Use scan data and a visual inspection before replacing sensors.

At a glance

Question Short answer Next move
Can I drive? Usually driveable if the engine runs normally, but do not ignore rough running, poor fuel economy, or multiple fuel-trim codes. Keep trips short if it runs normally; stop if symptoms get worse.
Likely cost Often a moderate sensor or wiring repair; bank and sensor location must be confirmed before parts are ordered. Get a written diagnosis before buying parts.
Check first Confirm bank 2 sensor 1 location, then check the connector, heater fuse feed, and wiring near the exhaust. Start with the cheap visible checks.

Can I still drive with this?

Drive with caution

Usually driveable if the engine runs normally, but do not ignore rough running, poor fuel economy, or multiple fuel-trim codes.

SeverityModerate

Moderate

Diagnostic flow

  1. What it meansThe heater circuit for the upstream oxygen sensor on bank 2 is…
  2. Check this firstConfirm bank 2 sensor 1 location for the exact engine.
  3. Likely causeUpstream O2 sensor heater failure
  4. Can you drive?Drive with caution

P0155 is an upstream O2 heater-circuit code. On many V engines, bank 2 means the side that does not contain cylinder 1, but confirm that before touching parts.

Because this is an upstream sensor, a real fault can affect fuel control more than a downstream monitor code. If it runs badly, limit driving.

Confirm bank 2 sensor 1 location, then check the connector, heater fuse feed, and wiring near the exhaust.

Structured DTC reference

What P0155 means

A fault in the bank 2 oxygen sensor heater circuit

A trouble code identifies the circuit or monitored condition that failed its test. It does not, by itself, identify the failed part or prove the same cause on every vehicle.

Severity and drivability

The code alone is not enough to assign one universal severity or “safe to drive” answer. Stop driving for loss of braking or steering, severe overheating, oil-pressure loss, a fuel leak or fire risk, or any rapidly worsening safety symptom.

Add the symptom contextChoose the vehicle

What it means

The heater circuit for the upstream oxygen sensor on bank 2 is drawing or reporting an unexpected electrical condition.

Common symptoms

  • Check-engine light
  • Reduced fuel economy
  • Sometimes rough running
  • Possible emissions failure

Likely causes

  • Upstream O2 sensor heater failure
  • Open or shorted heater circuit
  • Damaged connector
  • Low system voltage or fuse issue

Diagnosis steps

  1. Confirm bank 2 sensor 1 location for the exact engine.
  2. Check battery voltage and related fuses.
  3. Inspect wiring and connector condition.
  4. Test heater circuit before replacing the sensor.

What a mechanic should check

A mechanic should verify sensor location, heater-circuit voltage, ground, and resistance before replacing the O2 sensor.

Vehicle applicability

Generic OBD-II code across many makes and models; confirm service information for the exact vehicle.

Repair actions / cost band

$$ · Moderate

Often a moderate sensor or wiring repair; bank and sensor location must be confirmed before parts are ordered.

P0155 — vehicles with official records naming this code

P0155 is named in NHTSA-published manufacturer communications or investigations for 4 vehicle families, including:

A code named in a manufacturer communication means the document refers to it for those vehicles. It is not a diagnosis of any car, and it does not mean the code is common on that vehicle.

Frequently asked questions

What does P0155 mean?

the heater circuit for the upstream oxygen sensor on bank 2 is drawing or reporting an unexpected electrical condition.

Is P0155 safe to drive with?

Usually driveable if the engine runs normally, but do not ignore rough running, poor fuel economy, or multiple fuel-trim codes.

What should I check first?

Confirm bank 2 sensor 1 location, then check the connector, heater fuse feed, and wiring near the exhaust.

Continue exploring

Related codes

Known faults that trigger this code

Related symptoms

Keep going

Next diagnostic step

Check warning lights Use the dashboard light to decide what to do now. Trace the symptom Match what you can see, hear, smell, or feel. Find vehicle coverage Check model-year problem windows and related faults.

Source & evidence notes

  • What this is based on: generic OBD-II code references, EPA OBD background, and standard diagnostic practice.
  • This page is not based on complaint counts, repair-cost averages, or CarFaultIQ owner submissions.
  • Sources used: CarParts P0155 reference; US EPA OBD background.
  • URLs: https://www.carparts.com/blog/p0155-code-oxygen-sensor-heater-circuit-malfunction-bank-2-sensor-1/; https://19january2021snapshot.epa.gov/state-and-local-transportation/vehicle-emissions-board-diagnostics-obd_.html.
  • Confirm the exact diagnosis with live scan data, the owner manual, or service information for the specific vehicle.