Engine-CodesHonda – P0138 1996 Honda Civic

P0138 1996 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Quick Answer

The P0138 diagnostic trouble code (DTC) for a 1996 Honda Civic refers to a problem with the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 circuit, indicating that the sensor is detecting a low voltage condition. Common causes include Faulty HO2S Bank 1 Sensor 2, Damaged wiring or connectors, Blown fuse related to the sensor circuit. 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 1996 Honda Civic indicates HO2S Bank 1 Sensor 2 Circuit Low Voltage.
Common causes
Common causes include Faulty HO2S Bank 1 Sensor 2, Damaged wiring or connectors, Blown fuse related to the sensor circuit.
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 Sep 17, 2024
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Code P0138 1996 Honda Civic Description

The P0138 diagnostic trouble code (DTC) for a 1996 Honda Civic refers to a problem with the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 circuit, indicating that the sensor is detecting a low voltage condition. The HO2S is responsible for monitoring the oxygen content in the exhaust gases and providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. In this case, the low voltage reading from the sensor suggests that there is a problem with the sensor itself, the wiring, or the ECM.

OBDII Code P0138 1996 Honda Civic - HO2S Bank 1 Sensor 2 Circuit Low Voltage
P0138 1996 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Common Causes of P0138 1996 Honda Civic

  1. Faulty HO2S Bank 1 Sensor 2
  2. Damaged wiring or connectors
  3. Blown fuse related to the sensor circuit
  4. Malfunctioning ECM
  5. Exhaust leaks affecting sensor readings

Symptoms of P0138 1996 Honda Civic

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Hesitation or lack of acceleration
  4. Check Engine Light illuminated
  5. Increased emissions

How to Fix P0138 1996 Honda Civic

  1. Begin by conducting a visual inspection of the oxygen sensor, wiring, and connectors for any visible damage or corrosion.
  2. Test the sensor using a multimeter to check for proper voltage output and resistance.
  3. Check the fuse related to the sensor circuit to ensure it is not blown.
  4. If the sensor is faulty, replace it with a new OEM or high-quality aftermarket sensor.
  5. Clear the DTC using a scan tool and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0138 1996 Honda Civic

The typical repair costs for addressing a P0138 code on a 1996 Honda Civic can range from $150 to $300, including parts and labor. However, it is important to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less. It is recommended to inquire about local rates for a more accurate estimate.

Tech Notes for P0138 1996 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 1996 Honda Civic Code

1. What does the OBDII code P0138 on a 1996 Honda Civic mean?

The code P0138 indicates a problem with the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 Circuit, specifically low voltage.

2. What are the common symptoms of a P0138 error code on a 1996 Honda Civic?

Common symptoms include poor fuel economy, rough idling, engine misfires, and the illumination of the Check Engine Light.

3. What are the possible causes of a P0138 code on a 1996 Honda Civic?

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

4. How can I diagnose a P0138 code on my 1996 Honda Civic?

Diagnosing a P0138 code involves using an OBDII scanner to retrieve the code, inspecting the oxygen sensor and related wiring, checking for exhaust leaks, and testing the sensor's voltage output.

5. Can I drive my 1996 Honda Civic with a P0138 code?

It is not recommended to drive your vehicle with a P0138 code as it can lead to poor engine performance and potential damage to the catalytic converter.

6. How do I repair a P0138 code on my 1996 Honda Civic?

Repairing a P0138 code may involve replacing the oxygen sensor, repairing damaged wiring or connectors, fixing exhaust leaks, or addressing issues with the fuel system.

7. How much does it cost to fix a P0138 error code on a 1996 Honda Civic?

The cost of fixing a P0138 code can vary depending on the root cause of the issue. Replacing an oxygen sensor can cost between $100 to $300, while addressing other issues may increase the total repair cost.

8. Can a P0138 code on a 1996 Honda Civic cause emissions test failure?

Yes, a P0138 code can cause your vehicle to fail emissions testing due to increased emissions and poor fuel efficiency.

9. How often should the oxygen sensor be replaced on a 1996 Honda Civic?

The oxygen sensor should typically be replaced every 60,000 to 90,000 miles as part of regular maintenance to ensure optimal engine performance.

10. Are there any DIY tips for troubleshooting a P0138 code on a 1996 Honda Civic?

DIY tips include checking for visible wiring damage, ensuring proper sensor connections, and cleaning any debris around the sensor to see if the code clears before seeking professional assistance.

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