AutoCodes – Honda – P0138 1996 Honda Civic

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

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 1996 Honda Civic indicates HO2S Bank 1 Sensor 2 Circuit Low Voltage.
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 8,633

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 Mar 31, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0138 1996 Honda Civic 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 1996 Honda Civic - HO2S Bank 1 Sensor 2 Circuit Low Voltage - AutoCodes.com — P0138 1996 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 1996 Honda Civic?

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 1996 Honda Civic?

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 1996 Honda Civic 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.

Need more information about the P0138 1996 Honda Civic code?

Need more information on how to fix the P0138 1996 Honda Civic code? Get Access to Factory Service Manuals

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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.