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Engine-Codes – Honda – P0138 2008 Honda Accord

P0138 2008 Honda Accord Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Quick Answer

The P0138 diagnostic trouble code (DTC) specifically refers to the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 circuit registering a low voltage. Common causes include Faulty oxygen sensor, Wiring or connector damage, Exhaust system leaks. 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 2008 Honda Accord indicates HO2S Bank 1 Sensor 2 Circuit Low Voltage.
Common causes
Common causes include Faulty oxygen sensor, Wiring or connector damage, Exhaust system leaks.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 11, 2024
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Code P0138 2008 Honda Accord Description

The P0138 diagnostic trouble code (DTC) specifically refers to the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 circuit registering a low voltage. In simpler terms, this code indicates that the oxygen sensor downstream of the catalytic converter on bank 1 is not operating within the expected voltage range. The oxygen sensor plays a crucial role in monitoring the exhaust gases and providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion.

OBDII Code P0138 2008 Honda Accord - HO2S Bank 1 Sensor 2 Circuit Low Voltage
P0138 2008 Honda Accord Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Common Causes of P0138 2008 Honda Accord

  1. Faulty oxygen sensor
  2. Wiring or connector damage
  3. Exhaust system leaks
  4. ECM malfunction
  5. Poor fuel quality

Symptoms of P0138 2008 Honda Accord

  1. Decreased fuel efficiency
  2. Engine misfires or rough idling
  3. Illuminated check engine light
  4. Failed emissions test
  5. Reduced engine power

How to Fix P0138 2008 Honda Accord

  1. Diagnose the issue by using a scan tool to monitor the oxygen sensor's voltage readings and check for any wiring or connector damage.
  2. Replace the HO2S Bank 1 Sensor 2 if it is determined to be faulty. Ensure the replacement sensor is compatible with the vehicle's make and model.
  3. Inspect and repair any damaged wiring or connectors in the sensor circuit. Make sure all connections are secure and free of corrosion.
  4. Clear the DTC using the scan tool and test drive the vehicle to verify that the issue has been resolved. Monitor the oxygen sensor's voltage readings to ensure they are within the expected range.

Cost to Fix P0138 2008 Honda Accord

The typical repair costs for addressing a P0138 code on a 2008 Honda Accord can range from $150 to $400, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that diagnosis time and labor rates at auto repair shops can vary, with hourly rates typically falling between $80 and $150. Factors such as location, the vehicle's make and model, and the engine type can also influence the final repair costs. To obtain a more accurate estimate, it is advisable to consult with local auto repair shops or dealerships.

What does this mean?

Tech Notes for P0138 2008 Honda Accord

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

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.

Frequently Asked Questions about P0138 2008 Honda Accord Code

1. What are the common symptoms of OBDII code P0138 on a 2008 Honda Accord?

The common symptoms of OBDII code P0138 on a 2008 Honda Accord include poor fuel economy, rough idling, and the illumination of the check engine light.

2. What does HO2S Bank 1 Sensor 2 Circuit Low Voltage mean in relation to OBDII code P0138 on a 2008 Honda Accord?

HO2S stands for Heated Oxygen Sensor, and Bank 1 Sensor 2 refers to the downstream oxygen sensor located after the catalytic converter. The code P0138 indicates that the voltage from this sensor is lower than normal.

3. What are the possible causes of OBDII code P0138 on a 2008 Honda Accord?

The possible causes of OBDII code P0138 on a 2008 Honda Accord include a faulty oxygen sensor, wiring issues, exhaust leaks, or problems with the engine's air-fuel ratio.

4. How can I diagnose OBDII code P0138 on my 2008 Honda Accord?

To diagnose OBDII code P0138 on your 2008 Honda Accord, you can use an OBDII scanner to read the code, visually inspect the oxygen sensor and its wiring, check for exhaust leaks, and perform voltage tests on the sensor.

5. Can I drive my 2008 Honda Accord with OBDII code P0138?

It is not recommended to drive your 2008 Honda Accord with OBDII code P0138 for an extended period as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How can I repair OBDII code P0138 on my 2008 Honda Accord?

To repair OBDII code P0138 on your 2008 Honda Accord, you may need to replace the oxygen sensor, repair any wiring issues, fix exhaust leaks, or address any underlying engine issues causing the low voltage.

7. Is it possible to reset OBDII code P0138 on a 2008 Honda Accord without fixing the underlying issue?

Resetting OBDII code P0138 on a 2008 Honda Accord without fixing the underlying issue will only temporarily turn off the check engine light. The code is likely to reappear once the issue persists.

8. How much does it cost to fix OBDII code P0138 on a 2008 Honda Accord?

The cost to fix OBDII code P0138 on a 2008 Honda Accord can vary depending on the specific issue causing the low voltage condition. It may range from a few hundred to a thousand dollars, including parts and labor.

9. Can a DIY enthusiast fix OBDII code P0138 on a 2008 Honda Accord?

A DIY enthusiast with the necessary tools and knowledge of automotive repairs may be able to fix OBDII code P0138 on a 2008 Honda Accord, especially if the issue is related to the oxygen sensor or wiring.

10. Will OBDII code P0138 on a 2008 Honda Accord cause the vehicle to fail an emissions test?

Yes, OBDII code P0138 on a 2008 Honda Accord can cause the vehicle to fail an emissions test due to the abnormal voltage reading from the downstream oxygen sensor affecting the vehicle's emissions output.

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