AutoCodes – Honda – P0138 2000 Honda Civic

P0138 2000 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 2000 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 8,806

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 2000 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 2000 Honda Civic - HO2S Bank 1 Sensor 2 Circuit Low Voltage - AutoCodes.com — P0138 2000 Honda Civic Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2000 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 2000 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 2000 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 2000 Honda Civic code?

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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 2000 Honda Civic Code

1. What does OBDII code P0138 mean for a 2000 Honda Civic?

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

2. What are common symptoms of OBDII code P0138 on a 2000 Honda Civic?

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

3. What are possible causes of OBDII code P0138 on a 2000 Honda Civic?

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

4. How can I diagnose OBDII code P0138 on a 2000 Honda Civic?

- Diagnose P0138 by using an OBDII scanner to retrieve the code, visually inspecting the oxygen sensor and its wiring, checking for exhaust leaks, and conducting voltage tests.

5. Can I drive my 2000 Honda Civic with OBDII code P0138?

- It is not recommended to drive your vehicle with a P0138 code, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter over time.

6. How do I repair OBDII code P0138 on a 2000 Honda Civic?

- Repair options include replacing the oxygen sensor, repairing or replacing damaged wiring or connectors, fixing exhaust leaks, and addressing any issues with the fuel system.

7. Is it possible to reset OBDII code P0138 on a 2000 Honda Civic?

- You can reset the Check Engine Light and code temporarily, but it is important to address the underlying issue causing the P0138 code to prevent it from reoccurring.

8. How much does it cost to fix OBDII code P0138 on a 2000 Honda Civic?

- The cost of fixing P0138 can vary depending on the root cause, but it may range from $100 to $500 or more, including parts and labor.

9. Can a DIY enthusiast fix OBDII code P0138 on a 2000 Honda Civic?

- Depending on the skill level, a DIY enthusiast can potentially fix P0138 by replacing the oxygen sensor or addressing wiring issues, but professional diagnosis may be necessary for more complex problems.

10. How often does OBDII code P0138 occur in a 2000 Honda Civic?

- OBDII code P0138 can occur occasionally in a 2000 Honda Civic, especially as the vehicle ages and components like the oxygen sensor deteriorate. Regular maintenance and inspections can help prevent this code from appearing frequently.