AutoCodes – Honda – P0138 2009 Honda Accord

P0138 2009 Honda Accord 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 2009 Honda Accord 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.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 8,603

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 Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0138 2009 Honda Accord 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 2009 Honda Accord - HO2S Bank 1 Sensor 2 Circuit Low Voltage - AutoCodes.com — P0138 2009 Honda Accord Code - HO2S Bank 1 Sensor 2 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2009 Honda Accord?

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 2009 Honda Accord?

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 2009 Honda Accord 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 2009 Honda Accord code?

Need more information on how to fix the P0138 2009 Honda Accord code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0138 2009 Honda Accord code diagnosed by a professional: Find a repair shop in your area

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 2009 Honda Accord Code

1. What does OBDII code P0138 mean for a 2009 Honda Accord?

- OBDII code P0138 for a 2009 Honda Accord refers to the HO2S (Heated Oxygen Sensor) Bank 1 Sensor 2 Circuit Low Voltage.

2. What are the common symptoms of OBDII code P0138 in a 2009 Honda Accord?

- Common symptoms of P0138 in a 2009 Honda Accord may include poor fuel economy, rough idling, difficulty starting the engine, and an illuminated check engine light.

3. What are the possible causes of the HO2S Bank 1 Sensor 2 Circuit Low Voltage code in a 2009 Honda Accord?

- Possible causes of the P0138 code in a 2009 Honda Accord include a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks, or issues with the engine's air-fuel mixture.

4. How can I diagnose the HO2S Bank 1 Sensor 2 Circuit Low Voltage issue in my 2009 Honda Accord?

- To diagnose the P0138 code, you can use an OBDII scanner to read the code and check the voltage output of the oxygen sensor. Additionally, inspect the sensor's wiring and connectors for any signs of damage.

5. Can a dirty or contaminated oxygen sensor cause the P0138 code in a 2009 Honda Accord?

- Yes, a dirty or contaminated oxygen sensor can lead to the P0138 code in a 2009 Honda Accord as it may affect the sensor's ability to accurately measure the oxygen levels in the exhaust gases.

6. What are some repair tips for addressing the HO2S Bank 1 Sensor 2 Circuit Low Voltage issue in a 2009 Honda Accord?

- Repair tips for the P0138 code in a 2009 Honda Accord may include replacing the oxygen sensor, repairing damaged wiring or connectors, fixing any exhaust leaks, and ensuring proper engine maintenance.

7. Is it safe to continue driving a 2009 Honda Accord with the P0138 code illuminated?

- It is generally not recommended to drive a 2009 Honda Accord with the P0138 code illuminated, as it can lead to decreased fuel efficiency and potentially cause damage to the engine over time.

8. How much can I expect to pay for repairing the HO2S Bank 1 Sensor 2 Circuit Low Voltage issue in a 2009 Honda Accord?

- The cost of repairing the P0138 code in a 2009 Honda Accord can vary depending on the specific cause of the issue, but it may range from $100 to $300 for parts and labor.

9. Can resetting the check engine light temporarily resolve the P0138 code in a 2009 Honda Accord?

- Resetting the check engine light may temporarily turn off the warning indicator, but it will not fix the underlying issue causing the P0138 code in a 2009 Honda Accord. It is recommended to diagnose and address the problem promptly.

10. How often should I replace the oxygen sensors in a 2009 Honda Accord to prevent recurring P0138 codes?

- Oxygen sensors typically have a lifespan of around 100,000 miles, but it is advisable to follow the manufacturer's recommendations for sensor replacement intervals to prevent recurring P0138 codes in a 2009 Honda Accord.