Engine-CodesToyota – P0155 Toyota

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

Quick Answer

The P0155 diagnostic trouble code (DTC) for Toyota vehicles indicates a malfunction in the O2 sensor heater circuit for Bank 2 Sensor 1. Common causes include Faulty O2 sensor heater circuit, Wiring issues or shorts in the heater circuit, Blown fuse related to the O2 sensor. 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 O2 sensor heater circuit, Wiring issues or shorts in the heater circuit, Blown fuse related to the O2 sensor.
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.
Table of contents Created and updated by William Orellana on Aug 30, 2024
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Code P0155 Toyota Description

The P0155 diagnostic trouble code (DTC) for Toyota vehicles indicates a malfunction in the O2 sensor heater circuit for Bank 2 Sensor 1. This sensor is responsible for monitoring the oxygen levels in the exhaust gases and providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. The heater circuit in the sensor helps it reach operating temperature quickly for accurate readings. When this circuit malfunctions, it can lead to inaccurate sensor readings, which can affect the engine's performance and emissions.

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

Common Causes of P0155 Toyota

  1. Faulty O2 sensor heater circuit
  2. Wiring issues or shorts in the heater circuit
  3. Blown fuse related to the O2 sensor
  4. ECM software malfunction
  5. Exhaust leaks near the O2 sensor

Symptoms of P0155 Toyota

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Engine misfires
  4. Check engine light illuminated on the dashboard
  5. Failed emissions test

How to Fix P0155 Toyota

  1. Diagnose the issue using a scan tool to confirm the P0155 code and check the sensor's wiring and connections.
  2. Test the O2 sensor heater circuit for continuity and resistance to determine if the sensor itself is faulty.
  3. Replace the O2 sensor if necessary, ensuring the new sensor is compatible with your Toyota vehicle.
  4. Check and replace any damaged wiring or connectors in the heater circuit.
  5. Clear the DTC and perform a test drive to verify that the issue has been resolved.

Cost to Fix P0155 Toyota

The cost of repairing a P0155 code on a Toyota vehicle can vary depending on the specific model, year, and the extent of the issue. Typically, the price for a new O2 sensor can range from $50 to $200, while labor costs for diagnosis and replacement can add another $100 to $200. Overall, you can expect to pay anywhere from $150 to $400 for parts and labor. Keep in mind that these estimates are general guidelines, and prices may differ based on your location and the auto repair shop you choose. It's recommended to get multiple quotes to ensure you're getting a fair price for the repair.

Tech Notes for P0155 Toyota

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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When is the Code Detected?

The current amperage in the front heated oxygen sensor heater circuit is out of the normal range. (An improper voltage drop signal is sent to ECM through the front heated oxygen sensor heater)

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Information for Specific Toyota Models

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.

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