AutoCodes – Toyota – P0155 Toyota

P0155 Toyota Code - O2 Sensor Heater Circuit Bank 2 Sensor 1

Quick Answer

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0155 Toyota indicates O2 Sensor Heater Circuit Bank 2 Sensor 1.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 67,966

How popular is this code, among other codes? Medium

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 23, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0155 Toyota Description

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. The faster the heated oxygen sensor reaches that temperature the faster the sensor will start sending an accurate signal to the Engine Control Module (ECM). In order to achieve the require temperature, a heater element is included inside the heated oxygen sensor. The ECM controls the heated oxygen sensor heater element based on signals from the engine coolant temperature and engine load. The ECM controls the heater element circuit by allowing current flow to ground. The ECM monitors the voltage signal received through the heater element circuit and determines the state of the circuit by comparing the voltage detected with the factory specifications.

OBDII Code P0155 Toyota - O2 Sensor Heater Circuit Bank 2 Sensor 1 - AutoCodes.com — P0155 Toyota Code - O2 Sensor Heater Circuit Bank 2 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P0155 Toyota?

Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0155 Toyota?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The Engine Control Module (ECM) monitors how long it take the sensor to warm up and start sending an adequate signal. The code means the the sensor is taking too long to warm up. Replacing the Front Heated Oxygen Sensor (H2OS) Bank 2 usually takes care of the problem.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0155 Toyota code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific Toyota Models

P0155 Toyota RAV4 — Oxygen Sensor Heater Circuit Malfunction Bank 2 Sensor 1

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0155 Toyota Code

1. What does the OBDII code P0155 mean on a Toyota?

P0155 indicates a fault in the oxygen sensor heater circuit for Bank 2, Sensor 1. The sensor's internal heater is not functioning correctly.

2. What are the symptoms of code P0155 on a Toyota?

Common symptoms include the check engine light turning on, increased fuel consumption, rough idling, and poor engine performance.

3. What causes the P0155 code to appear on my Toyota?

Possible causes include a faulty oxygen sensor, damaged wiring or connectors, a blown fuse for the heater circuit, or a malfunctioning Engine Control Module (ECM).

4. How do I know which sensor is Bank 2, Sensor 1 in my Toyota?

Bank 2 refers to the side of the engine opposite Bank 1 (usually the side of cylinder 2 in a V-engine), and Sensor 1 is the upstream oxygen sensor located before the catalytic converter.

5. Can I drive my Toyota with the P0155 code?

While it may be possible to drive, it is not recommended. The faulty heater circuit can affect fuel efficiency and emissions, potentially causing further engine damage.

6. How do I fix the P0155 code on a Toyota?

Repairs may include replacing the oxygen sensor, repairing damaged wiring or connectors, checking and replacing the fuse, or updating/replacing the ECM if necessary.

7. How much does it cost to fix the P0155 code on a Toyota?

The cost of replacing an oxygen sensor typically ranges from $150 to $400, including parts and labor. Wiring repairs or ECM replacement can vary depending on the issue.

8. How can I diagnose the P0155 code on my Toyota?

Use a scan tool to confirm the code, visually inspect the oxygen sensor and wiring, check for blown fuses, and test the heater circuit's resistance with a multimeter.

9. Is the P0155 code specific to Toyota vehicles?

No, the P0155 code is a generic OBDII code that can occur in vehicles from various manufacturers, but the exact repair process may differ by make and model.

10. What happens if I ignore the P0155 code on my Toyota?

Ignoring the code can lead to reduced fuel economy, increased emissions, and potential damage to other engine components, such as the catalytic converter.