Engine-CodesToyota – P0138 Toyota RAV4

P0138 Toyota RAV4 Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Quick Answer

The P0138 diagnostic trouble code (DTC) for a Toyota RAV4 indicates that there is a high voltage condition in the oxygen sensor circuit for Bank 1 Sensor 2. Common causes include Faulty oxygen sensor, Wiring or connector issues in the oxygen sensor circuit, Exhaust leaks near the 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
P0138 Toyota RAV4 indicates Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2.
Common causes
Common causes include Faulty oxygen sensor, Wiring or connector issues in the oxygen sensor circuit, Exhaust leaks near the 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 18, 2024
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Code P0138 Toyota RAV4 Description

The P0138 diagnostic trouble code (DTC) for a Toyota RAV4 indicates that there is a high voltage condition in the oxygen sensor circuit for Bank 1 Sensor 2. This sensor is located downstream of the catalytic converter and is responsible for monitoring the oxygen levels in the exhaust gases. The high voltage reading suggests that the sensor is detecting a rich air-fuel mixture in the exhaust, potentially leading to an incorrect fuel trim calculation by the engine control module (ECM). This issue can negatively impact the vehicle's fuel efficiency, emissions levels, and overall performance.

OBDII Code P0138 Toyota RAV4 - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2
P0138 Toyota RAV4 Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Common Causes of P0138 Toyota RAV4

  1. Faulty oxygen sensor
  2. Wiring or connector issues in the oxygen sensor circuit
  3. Exhaust leaks near the sensor
  4. Engine running too rich due to a faulty fuel injector
  5. ECM software or hardware malfunction

Symptoms of P0138 Toyota RAV4

  1. Decreased fuel efficiency
  2. Check Engine Light illuminated
  3. Rough idling or engine misfires
  4. Increased emissions output
  5. Reduced engine performance

How to Fix P0138 Toyota RAV4

  1. Use an OBD-II scanner to confirm the P0138 code and pinpoint the specific issue.
  2. Inspect the wiring and connectors of Bank 1 Sensor 2 for any damage or corrosion.
  3. Test the oxygen sensor's voltage output using a multimeter to determine if it is functioning properly.
  4. Replace the oxygen sensor if it is determined to be faulty.
  5. Clear the DTC and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0138 Toyota RAV4

The cost of repairing a P0138 code on a Toyota RAV4 can vary depending on the specific cause of the issue. In general, replacing an oxygen sensor can range from $150 to $400, including parts and labor. Additional costs may apply if wiring repairs or ECM diagnostics are needed. As mentioned earlier, labor rates at auto repair shops can vary, so it's recommended to obtain quotes from local shops to get a more accurate estimate.

Tech Notes for P0138 Toyota RAV4

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.





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When is the Code Detected?

The P0138 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor signal voltage remains excessively high for an extended period of time.

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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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