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Engine-Codes – Honda – P0138 1999 Honda Civic

P0138 1999 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Quick Answer

The P0138 diagnostic trouble code (DTC) for a 1999 Honda Civic specifically refers to the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 Circuit Low Voltage. Common causes include Faulty oxygen sensor, Wiring or connector issues in the sensor circuit, 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 1999 Honda Civic indicates HO2S Bank 1 Sensor 2 Circuit Low Voltage.
Common causes
Common causes include Faulty oxygen sensor, Wiring or connector issues in the sensor circuit, 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 17, 2024
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Code P0138 1999 Honda Civic Description

The P0138 diagnostic trouble code (DTC) for a 1999 Honda Civic specifically refers to the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 Circuit Low Voltage. This code indicates that the oxygen sensor located 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 amount of oxygen in the exhaust gases, which helps the engine control module (ECM) adjust the air-fuel mixture for optimal combustion efficiency.

OBDII Code P0138 1999 Honda Civic - HO2S Bank 1 Sensor 2 Circuit Low Voltage
P0138 1999 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

Common Causes of P0138 1999 Honda Civic

  1. Faulty oxygen sensor
  2. Wiring or connector issues in the sensor circuit
  3. Exhaust system leaks
  4. Engine misfires
  5. Fuel system problems

Symptoms of P0138 1999 Honda Civic

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Engine misfires
  4. Increased emissions
  5. Check engine light illuminated

How to Fix P0138 1999 Honda Civic

  1. Diagnose the issue by using a scan tool to retrieve the specific DTC and monitor the oxygen sensor's voltage readings.
  2. Inspect the wiring and connectors for any damage or corrosion. Repair or replace as necessary.
  3. Test the oxygen sensor's functionality using a multimeter to check for proper voltage output.
  4. Replace the HO2S Bank 1 Sensor 2 if it is determined to be faulty.
  5. Clear the DTC and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0138 1999 Honda Civic

The cost of repairing the HO2S Bank 1 Sensor 2 Circuit Low Voltage code on a 1999 Honda Civic can vary depending on the specific cause of the issue. In general, the price range for parts can be between $50 to $200, while labor costs can range from $100 to $300. Overall, the total repair cost could fall between $150 to $500. It's important to note that these estimates are approximate and can fluctuate based on factors such as location, shop rates, and the extent of the repair needed. It's recommended to consult with a trusted mechanic or auto repair shop for a more accurate cost assessment.

What does this mean?

Tech Notes for P0138 1999 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 1999 Honda Civic Code

1. What does OBDII code P0138 on my 1999 Honda Civic mean?

This code indicates a problem with the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 circuit, specifically low voltage detected.

2. What are the common symptoms of HO2S Bank 1 Sensor 2 Circuit Low Voltage issue?

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

3. What are the possible causes of the P0138 code on a 1999 Honda Civic?

Potential causes include a faulty oxygen sensor, wiring issues in the sensor circuit, exhaust leaks, engine misfires, or a malfunctioning catalytic converter.

4. How can I diagnose the HO2S Bank 1 Sensor 2 Circuit Low Voltage problem on my Honda Civic?

Diagnosis typically involves inspecting the oxygen sensor and its wiring for damage, checking for exhaust leaks, testing the sensor's voltage output, and scanning for other related trouble codes.

5. Can I drive my 1999 Honda Civic with the P0138 code?

It is not recommended to drive for an extended period with this code, as it can negatively affect engine performance and emissions. Seek a professional diagnosis and repair as soon as possible.

6. How do I repair the HO2S Bank 1 Sensor 2 Circuit Low Voltage issue on my Honda Civic?

Repair options may include replacing the oxygen sensor, repairing damaged wiring, fixing exhaust leaks, addressing engine misfires, or replacing a faulty catalytic converter.

7. Is it possible to clear the P0138 code on a 1999 Honda Civic without fixing the issue?

Clearing the code without addressing the underlying problem will only temporarily turn off the Check Engine Light. The issue will persist and may lead to further complications.

8. Can a dirty MAF sensor cause the P0138 code on a 1999 Honda Civic?

While a dirty MAF sensor can impact engine performance, it is not a common cause of the P0138 code specifically. Focus on diagnosing the oxygen sensor circuit and related components.

9. Will the P0138 code on my 1999 Honda Civic cause a vehicle to fail emissions tests?

Yes, a vehicle with the P0138 code may fail emissions tests due to increased emissions and poor overall performance. It is advisable to address the issue before undergoing an emissions test.

10. How much does it typically cost to repair the HO2S Bank 1 Sensor 2 Circuit Low Voltage issue on a 1999 Honda Civic?

The cost of repairs can vary depending on the exact cause of the problem and the required parts and labor. On average, expect to pay between $100 to $300 for parts and labor.

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