Engine-CodesToyota – P0155 Toyota RAV4

P0155 Toyota RAV4 Code - Oxygen Sensor Heater Circuit Malfunction Bank 2 Sensor 1

Quick Answer

The P0155 diagnostic trouble code (DTC) for a Toyota RAV4 indicates an Oxygen Sensor Heater Circuit Malfunction in Bank 2 Sensor 1. Common causes include Faulty Oxygen Sensor: The most common cause of the P0155 code is a faulty oxygen sensor with a malfunctioning heater circuit, Wiring Issues: Damaged or corroded wiring connecting the oxygen sensor to the ECM can disrupt the heater circuit operation, Blown Fuse: A blown fuse in the oxygen sensor heater circuit can prevent the sensor from receiving power to heat up. 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 RAV4 indicates Oxygen Sensor Heater Circuit Malfunction Bank 2 Sensor 1 .
Common causes
Common causes include Faulty Oxygen Sensor: The most common cause of the P0155 code is a faulty oxygen sensor with a malfunctioning heater circuit, Wiring Issues: Damaged or corroded wiring connecting the oxygen sensor to the ECM can disrupt the heater circuit operation, Blown Fuse: A blown fuse in the oxygen sensor heater circuit can prevent the sensor from receiving power to heat up.
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 Sep 14, 2024
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Code P0155 Toyota RAV4 Description

The P0155 diagnostic trouble code (DTC) for a Toyota RAV4 indicates an Oxygen Sensor Heater Circuit Malfunction in Bank 2 Sensor 1. This means that there is an issue with the heating element of the oxygen sensor located in the exhaust system. The oxygen sensor plays a crucial role in monitoring the oxygen levels in the exhaust gases, providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion.

OBDII Code P0155 Toyota RAV4 - Oxygen Sensor Heater Circuit Malfunction Bank 2 Sensor 1
P0155 Toyota RAV4 Code - Oxygen Sensor Heater Circuit Malfunction Bank 2 Sensor 1

Common Causes of P0155 Toyota RAV4

  1. Faulty Oxygen Sensor: The most common cause of the P0155 code is a faulty oxygen sensor with a malfunctioning heater circuit.
  2. Wiring Issues: Damaged or corroded wiring connecting the oxygen sensor to the ECM can disrupt the heater circuit operation.
  3. Blown Fuse: A blown fuse in the oxygen sensor heater circuit can prevent the sensor from receiving power to heat up.
  4. ECM Malfunction: A malfunctioning engine control module (ECM) may not be sending the proper signals to the oxygen sensor heater circuit.
  5. Exhaust Leak: An exhaust leak near the oxygen sensor can affect its performance and trigger the P0155 code.

Symptoms of P0155 Toyota RAV4

  1. Check Engine Light: The most common symptom associated with the P0155 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Decreased Fuel Efficiency: A malfunctioning oxygen sensor heater circuit can lead to decreased fuel efficiency as the engine may not be running at optimal air-fuel ratios.
  3. Rough Idling: The engine may experience rough idling or hesitation when the oxygen sensor is not functioning properly.
  4. Increased Emissions: A faulty oxygen sensor can cause increased emissions, potentially leading to a failed emissions test.
  5. Engine Misfires: In severe cases, the engine may experience misfires due to incorrect air-fuel mixture adjustments.

How to Fix P0155 Toyota RAV4

  1. Diagnose the Issue: Use an OBD-II scanner to retrieve the specific DTC and confirm the P0155 code. Inspect the wiring, fuse, and oxygen sensor for any visible damage.
  2. Replace Oxygen Sensor: If the oxygen sensor is determined to be faulty, replace Bank 2 Sensor 1 with a new one. Ensure the replacement sensor is compatible with the vehicle's make and model.
  3. Check Wiring: Inspect the wiring harness for any signs of damage or corrosion. Repair or replace any damaged wires as needed.
  4. Test Oxygen Sensor: After replacing the oxygen sensor, clear the DTC and test drive the vehicle to ensure the P0155 code does not return. Use the OBD-II scanner to monitor the oxygen sensor's performance.
  5. Verify Repairs: Once the repair process is complete, verify that the check engine light is no longer illuminated and that the vehicle's performance has improved.

Cost to Fix P0155 Toyota RAV4

The typical repair costs for addressing a P0155 code in a Toyota RAV4 can range from $150 to $400, depending on the cost of the oxygen sensor, labor rates, and any additional parts or repairs needed. It's important to note that diagnosis time and labor rates at auto repair shops can vary, with hourly rates typically ranging between $80 and $150. Factors such as location, vehicle make and model, and engine type can also impact the overall repair costs. To obtain a more accurate estimate, it is recommended to consult with local auto repair shops for specific pricing information.

Tech Notes for P0155 Toyota RAV4

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.

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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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.

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