AutoCodes – Honda – P0138 1997 Honda Civic

P0138 1997 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 1997 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 7,211

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 1997 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 1997 Honda Civic - HO2S Bank 1 Sensor 2 Circuit Low Voltage - AutoCodes.com — P0138 1997 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 1997 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 1997 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 1997 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 1997 Honda Civic code?

Need more information on how to fix the P0138 1997 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 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.