Engine-CodesSubaru – P0140 Subaru

P0140 Subaru Code - HO2S12 No Activity Detected

Quick Answer

The P0140 code for Subaru vehicles indicates that the Heated Oxygen Sensor (HO2S) located after the catalytic converter on bank 1, sensor 2, is not sending any signal or activity to the Engine Control Module (ECM). Common causes include Faulty HO2S sensor, Wiring or connector issues, Exhaust leaks near the sensor. 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
P0140 Subaru indicates HO2S12 No Activity Detected.
Common causes
Common causes include Faulty HO2S sensor, Wiring or connector issues, Exhaust leaks near the sensor.
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.
Table of contents Created and updated by William Orellana on Sep 06, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0140 Subaru Description

The P0140 code for Subaru vehicles indicates that the Heated Oxygen Sensor (HO2S) located after the catalytic converter on bank 1, sensor 2, is not sending any signal or activity to the Engine Control Module (ECM). This sensor is crucial for monitoring the oxygen content in the exhaust gases and adjusting the air-fuel mixture accordingly. When no activity is detected, it can lead to improper fuel mixture, decreased fuel efficiency, increased emissions, and potential damage to the catalytic converter. If left unresolved, the vehicle may experience drivability issues, rough idling, hesitation, and poor overall performance.

OBDII Code P0140 Subaru - HO2S12 No Activity Detected
P0140 Subaru Code - HO2S12 No Activity Detected

Common Causes of P0140 Subaru

  1. Faulty HO2S sensor.
  2. Wiring or connector issues.
  3. Exhaust leaks near the sensor.
  4. Exhaust system damage.
  5. ECM malfunction.

Symptoms of P0140 Subaru

  1. Check Engine Light illuminated on the dashboard.
  2. Decreased fuel efficiency.
  3. Rough idling or stalling.
  4. Engine misfires.
  5. Increased emissions.

How to Fix P0140 Subaru

  1. Begin by confirming the P0140 code with a diagnostic scan tool.
  2. Inspect the wiring and connectors for any damage or corrosion. Repair or replace as needed.
  3. Check for exhaust leaks near the sensor and repair them.
  4. Test the HO2S sensor using a multimeter to ensure it is functioning properly. Replace if necessary.
  5. Clear the code and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix P0140 Subaru

The typical repair costs for addressing a P0140 code on a Subaru vehicle can range from $100 to $300, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that diagnosis time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate.

Tech Notes for P0140 Subaru

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

When is the Code Detected?

The P0140 code is set when the voltage signal sent from the sensor to the Engine Control Module is constant.

Need more information about the P0140 Subaru code?

Need more information on how to fix the P0140 Subaru code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0140 Subaru 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 P0140 Subaru Code

1. What are the common symptoms of OBDII code P0140 in a Subaru?

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

2. What does the OBDII code P0140 Subaru - HO2S12 No Activity Detected mean?

- This code indicates that the oxygen sensor (HO2S12) located after the catalytic converter is not sending any signals or is not functioning properly.

3. What are the possible causes of the HO2S12 No Activity Detected error code?

- Common causes 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 issue causing the P0140 code in my Subaru?

- To diagnose the problem, you can use an OBDII scanner to read the code, visually inspect the oxygen sensor and its connections, check for exhaust leaks, and perform voltage tests on the sensor.

5. Can I continue driving my Subaru with the P0140 code present?

- It is not recommended to drive with the P0140 code as it can lead to decreased fuel efficiency and potential damage to the catalytic converter over time.

6. How can I repair the HO2S12 No Activity Detected issue in my Subaru?

- Repair options may include replacing the oxygen sensor, repairing damaged wiring or connectors, fixing exhaust leaks, and ensuring the air-fuel mixture is within the correct parameters.

7. Are there any DIY tips for resolving the P0140 error code in a Subaru?

- DIY tips may include checking and cleaning the oxygen sensor connections, inspecting the sensor for physical damage, and ensuring there are no exhaust leaks in the system.

8. How much does it typically cost to fix the OBDII code P0140 in a Subaru?

- The cost of repairs can vary depending on the specific issue, but replacing an oxygen sensor can range from $100 to $300, while addressing exhaust leaks or wiring problems may incur additional costs.

9. Can a P0140 error code be triggered by issues other than the oxygen sensor?

- Yes, other issues such as exhaust leaks, wiring problems, or issues with the engine's air-fuel mixture can also trigger the P0140 code in a Subaru.

10. How often should I have my Subaru's oxygen sensors inspected to prevent the P0140 code from occurring?

- It is recommended to have your oxygen sensors inspected during routine maintenance intervals, typically every 30,000 to 50,000 miles, to help prevent issues like the P0140 code from occurring.

Discuss the causes and fixes for P0140 Subaru OBDII Code

Code P0140 Subaru comments

No comments found for this page.