AutoCodes – Toyota – P0138 2006 Toyota Prius

P0138 2006 Toyota Prius Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Quick Answer

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. 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 2006 Toyota Prius indicates Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
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 10,731

How popular is this code, among other codes? Low

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 Jul 04, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0138 2006 Toyota Prius Description

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

OBDII Code P0138 2006 Toyota Prius - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2 - AutoCodes.com — P0138 2006 Toyota Prius Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0138 2006 Toyota Prius?

Faulty Rear Heated Oxygen Sensor Bank 1
Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
Intake air leaks
Exhaust gas leaks
Inappropriate fuel pressure
Faulty fuel injectors

How to Fix the DTC P0138 2006 Toyota Prius?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0138 2006 Toyota Prius 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.

Need more information about the P0138 2006 Toyota Prius code?

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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.

Frequently Asked Questions about P0138 2006 Toyota Prius Code

1. What does the OBDII code P0138 for a 2006 Toyota Prius indicate?

- This code refers to an Oxygen Sensor Circuit High Voltage condition on Bank 1 Sensor 2 in the exhaust system.

2. What are the common symptoms associated with the P0138 code in a 2006 Toyota Prius?

- Common symptoms include poor fuel economy, a drop in engine performance, rough idling, and the illumination of the Check Engine Light.

3. What are the possible causes of the P0138 code on a 2006 Toyota Prius?

- The main causes of this code can include a faulty oxygen sensor, wiring issues in the oxygen sensor circuit, or an engine running too rich.

4. How can I diagnose the P0138 code on my 2006 Toyota Prius?

- To diagnose this code, you can use a scan tool to read the code, visually inspect the oxygen sensor and its wiring, and perform voltage testing on the sensor.

5. Can I drive my 2006 Toyota Prius with the P0138 code?

- It is not recommended to drive your vehicle with the P0138 code present, as it can lead to other issues and cause potential damage to the engine or catalytic converter.

6. How can I repair the P0138 code on my 2006 Toyota Prius?

- The typical repair for this code involves replacing the oxygen sensor on Bank 1 Sensor 2 and addressing any wiring issues in the circuit.

7. Are there any DIY tips for fixing the P0138 code on a 2006 Toyota Prius?

- While replacing the oxygen sensor yourself is possible, it's recommended to have a professional diagnose and repair the issue to ensure it is fixed correctly.

8. How much does it cost to fix the P0138 code on a 2006 Toyota Prius?

- The cost of fixing the P0138 code can vary depending on the cause of the issue, but it typically ranges from $200 to $400 for parts and labor.

9. How often should the oxygen sensors be replaced in a 2006 Toyota Prius?

- Oxygen sensors generally have a lifespan of around 100,000 miles, but they can fail prematurely due to various factors like poor fuel quality or engine issues.

10. Will resetting the Check Engine Light make the P0138 code disappear on a 2006 Toyota Prius?

- Resetting the Check Engine Light may temporarily turn it off, but if the underlying issue causing the P0138 code is not addressed, the light will likely come back on.