AutoCodes – Scion – P0138 2007 Scion xB

P0138 2007 Scion xB 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 2007 Scion xB 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 3,647

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 Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0138 2007 Scion xB 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 2007 Scion xB - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2 - AutoCodes.com — P0138 2007 Scion xB Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0138 2007 Scion xB?

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 2007 Scion xB?

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

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0138 2007 Scion xB 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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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 2007 Scion xB Code

1. What does the OBDII code P0138 on a 2007 Scion xB mean?

The code P0138 indicates that there is a high voltage condition in the oxygen sensor circuit of Bank 1 Sensor 2 in the exhaust system.

2. What are some common symptoms of a P0138 code in a 2007 Scion xB?

Common symptoms of a P0138 code may include poor fuel economy, rough idling, engine hesitation, and an illuminated check engine light on the dashboard.

3. What are the possible causes of a P0138 code in a 2007 Scion xB?

Potential causes of a P0138 code include a faulty oxygen sensor, wiring issues in the sensor circuit, exhaust leaks, or a problem with the engine's fuel system.

4. How can I diagnose a P0138 code in my 2007 Scion xB?

Diagnosing a P0138 code typically involves using an OBDII scanner to read the code, inspecting the oxygen sensor and its wiring for damage, checking for exhaust leaks, and testing the sensor's voltage.

5. Can I drive my 2007 Scion xB with a P0138 code?

It is not recommended to drive your vehicle with a P0138 code for an extended period as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How can I repair a P0138 code in my 2007 Scion xB?

To repair a P0138 code, you may need to replace the oxygen sensor (Bank 1 Sensor 2), repair any damaged wiring, fix exhaust leaks, or address any issues with the fuel system.

7. Will resetting the check engine light fix a P0138 code in a 2007 Scion xB?

Resetting the check engine light may temporarily clear the code, but if the underlying issue causing the P0138 code is not addressed, the light is likely to come back on.

8. How much does it cost to fix a P0138 code in a 2007 Scion xB?

The cost of fixing a P0138 code can vary depending on the specific issue causing the code. It is recommended to consult a mechanic for a proper diagnosis and cost estimate.

9. Can a P0138 code in a 2007 Scion xB cause other problems if left unresolved?

If left unresolved, a P0138 code can lead to decreased fuel efficiency, engine performance issues, and potential damage to the catalytic converter over time.

10. How often should the oxygen sensor be replaced in a 2007 Scion xB to prevent a P0138 code?

It is recommended to replace the oxygen sensor as part of regular maintenance every 60,000 to 90,000 miles to help prevent issues like the P0138 code from occurring.