AutoCodes – Toyota – P0136 2008 Toyota Prius

P0136 2008 Toyota Prius Code - HO2S12 Circuit Malfunction

Quick Answer

The heated oxygen sensor 2 (HO2S), 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: P0136 2008 Toyota Prius indicates HO2S12 Circuit Malfunction.
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 3,522

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
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Code P0136 2008 Toyota Prius Description

The heated oxygen sensor 2 (HO2S), 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 P0136 2008 Toyota Prius - HO2S12 Circuit Malfunction - AutoCodes.com — P0136 2008 Toyota Prius Code - HO2S12 Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0136 2008 Toyota Prius?

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
Inappropriate fuel pressure
Faulty fuel injectors
Intake air leaks may be faulty
Exhaust gas leaks

How to Fix the DTC P0136 2008 Toyota Prius?

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 P0136 2008 Toyota Prius 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 P0136 2008 Toyota Prius 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 P0136 2008 Toyota Prius Code

1. What does the OBDII code P0136 for a 2008 Toyota Prius indicate?

- The code P0136 on a 2008 Toyota Prius specifically refers to a malfunction in the HO2S12 (Heated Oxygen Sensor 1 Sensor 2) circuit.

2. What are common symptoms of the HO2S12 circuit malfunction in a 2008 Toyota Prius?

- Common symptoms include poor fuel efficiency, rough idling, stalling, and an illuminated check engine light.

3. What are the potential causes of the P0136 code in a 2008 Toyota Prius?

- Possible causes include a faulty oxygen sensor, wiring issues in the HO2S12 circuit, exhaust leaks, or a problem with the engine's air-fuel mixture.

4. How can I diagnose the HO2S12 circuit malfunction in my 2008 Toyota Prius?

- Diagnosing the issue involves using an OBDII scanner to read the error code, inspecting the wiring and connections related to the HO2S12 sensor, and performing a voltage test on the sensor.

5. Can I continue driving my 2008 Toyota Prius with the P0136 code present?

- It is not recommended to ignore the P0136 code, as it can lead to further damage and decreased performance. It's best to address the issue promptly.

6. How can I repair the HO2S12 circuit malfunction in my 2008 Toyota Prius?

- Depending on the root cause, repairs may involve replacing the oxygen sensor, repairing damaged wiring, fixing exhaust leaks, or addressing issues with the air-fuel mixture.

7. Is it possible to reset the P0136 code in a 2008 Toyota Prius without fixing the issue?

- While you can clear the code using an OBDII scanner, the underlying problem causing the code will persist until properly addressed.

8. How much does it typically cost to fix the HO2S12 circuit malfunction in a 2008 Toyota Prius?

- The cost of repairs can vary based on the specific cause of the issue, but it may range from $100 for a DIY oxygen sensor replacement to a few hundred dollars for more complex repairs at a mechanic.

9. Can a faulty HO2S12 sensor affect the overall performance of my 2008 Toyota Prius?

- Yes, a malfunctioning HO2S12 sensor can impact fuel efficiency, engine performance, and emissions output in your 2008 Toyota Prius.

10. How often should I check the oxygen sensors in my 2008 Toyota Prius to prevent issues like the P0136 code?

- It is recommended to have the oxygen sensors inspected during regular maintenance intervals or whenever you experience symptoms of poor engine performance.