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P0138 1997 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Quick Answer

The OBD-II code P0138 for a 1997 Honda Civic refers to an issue with the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 Circuit having low voltage. Common causes include Faulty oxygen sensor, Damaged wiring or connectors, 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 1997 Honda Civic indicates HO2S Bank 1 Sensor 2 Circuit Low Voltage.
Common causes
Common causes include Faulty oxygen sensor, Damaged wiring or connectors, 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0138 1997 Honda Civic Description

The OBD-II code P0138 for a 1997 Honda Civic refers to an issue with the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 Circuit having low voltage. The oxygen sensor is a crucial component of the vehicle's emissions system, responsible for measuring the oxygen levels in the exhaust gases and providing feedback to the engine control module (ECM) for optimal fuel efficiency and emission control.

OBDII Code P0138 1997 Honda Civic - HO2S Bank 1 Sensor 2 Circuit Low Voltage
P0138 1997 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Common Causes of P0138 1997 Honda Civic

  1. Faulty oxygen sensor
  2. Damaged wiring or connectors
  3. Exhaust leaks near the sensor
  4. Issues with the catalytic converter
  5. ECM software or hardware problems

Symptoms of P0138 1997 Honda Civic

  1. Decreased fuel efficiency
  2. Poor engine performance or hesitation
  3. Rough idling or stalling
  4. Increased emissions
  5. Check Engine Light (CEL) illuminated on the dashboard

How to Fix P0138 1997 Honda Civic

  1. Diagnose the issue: Use an OBD-II scanner to retrieve the specific trouble code and further diagnose the problem by checking the sensor's voltage readings and inspecting the wiring and connections.
  2. Replace the oxygen sensor: If the sensor is determined to be faulty, replace it with a new one. Ensure the replacement sensor is compatible with your vehicle's make and model.
  3. Check wiring and connectors: Inspect the wiring harness and connectors for any signs of damage, corrosion, or loose connections. Repair or replace as needed.
  4. Inspect the catalytic converter: Check the condition of the catalytic converter for any damage or clogging that could be affecting the sensor readings. Replace if necessary.
  5. Clear the code: After making the repairs, clear the trouble code from the ECM memory using the OBD-II scanner. This will reset the Check Engine Light and allow you to monitor if the issue has been resolved.

Cost to Fix P0138 1997 Honda Civic

The cost of repairing a P0138 code on a 1997 Honda Civic can vary depending on the specific cause of the issue. On average, the cost of replacing an oxygen sensor can range from $100 to $250, including parts and labor. If additional repairs are needed, such as fixing wiring or replacing the catalytic converter, the total cost could increase significantly.

What does this mean?

Tech Notes for P0138 1997 Honda Civic

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 1997 Honda Civic Code

1. What does the OBDII code P0138 mean for a 1997 Honda Civic?

- The code P0138 indicates that the downstream oxygen sensor (Bank 1 Sensor 2) in the exhaust system is detecting low voltage.

2. What are the common symptoms of HO2S Bank 1 Sensor 2 Circuit Low Voltage in a 1997 Honda Civic?

- Common symptoms include poor fuel efficiency, rough idling, engine hesitation, and an illuminated check engine light.

3. What can cause the HO2S Bank 1 Sensor 2 Circuit Low Voltage code in a 1997 Honda Civic?

- Potential causes include a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks, or issues with the engine's fuel system.

4. How can I diagnose the HO2S Bank 1 Sensor 2 Circuit Low Voltage issue in my 1997 Honda Civic?

- Diagnosis involves using an OBDII scanner to read the code, inspecting the sensor and its wiring for damage, and checking for exhaust leaks.

5. Is it safe to continue driving with the P0138 code on a 1997 Honda Civic?

- While the vehicle may still be operable, it's recommended to address the issue promptly to prevent potential damage to the catalytic converter and other components.

6. Can I repair the HO2S Bank 1 Sensor 2 Circuit Low Voltage problem in my 1997 Honda Civic myself?

- Depending on your skill level, you may be able to replace the oxygen sensor or repair wiring issues yourself. However, professional diagnosis is recommended for accuracy.

7. How much does it cost to fix the P0138 code in a 1997 Honda Civic?

- The cost of repairs can vary depending on the exact cause of the issue, but it typically ranges from $100 to $300 for parts and labor.

8. How often should the oxygen sensors be replaced in a 1997 Honda Civic?

- Oxygen sensors generally have a lifespan of 60,000 to 100,000 miles. It's recommended to follow the manufacturer's maintenance schedule for sensor replacement.

9. Will resetting the check engine light resolve the P0138 code in a 1997 Honda Civic?

- Resetting the light will clear the code temporarily, but if the underlying issue is not addressed, the code is likely to reappear after driving the vehicle.

10. Can a faulty oxygen sensor cause other problems in a 1997 Honda Civic besides triggering the P0138 code?

- Yes, a faulty oxygen sensor can lead to decreased fuel efficiency, engine performance issues, increased emissions, and potential damage to the catalytic converter over time.

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