AutoCodes – Toyota – P0136 2005 Toyota Prius

P0136 2005 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 2005 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 5,555

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 2005 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 2005 Toyota Prius - HO2S12 Circuit Malfunction - AutoCodes.com — P0136 2005 Toyota Prius Code - HO2S12 Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0136 2005 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 2005 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 2005 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 2005 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 2005 Toyota Prius Code

1. What does the OBDII code P0136 mean for a 2005 Toyota Prius?

- The code P0136 in a 2005 Toyota Prius indicates a malfunction in the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit.

2. What are the common symptoms of a HO2S12 circuit malfunction in a 2005 Toyota Prius?

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

3. What are the potential causes of the P0136 code in a 2005 Toyota Prius?

- The code P0136 can be triggered by issues such as a faulty HO2S12 sensor, wiring problems, exhaust system leaks, or a malfunctioning engine control module (ECM).

4. How can I diagnose the HO2S12 circuit malfunction in my 2005 Toyota Prius?

- Diagnosing the issue involves using an OBDII scanner to retrieve the code, checking the wiring and connectors for any damage, and testing the HO2S12 sensor's functionality.

5. Can I drive my 2005 Toyota Prius with the P0136 code?

- It is not recommended to drive your vehicle with the P0136 code as it can lead to poor engine performance and potentially cause damage to other components over time.

6. How can I repair the HO2S12 circuit malfunction in my 2005 Toyota Prius?

- Repairing the issue may involve replacing the HO2S12 sensor, repairing or replacing damaged wiring, fixing exhaust leaks, or reprogramming the ECM if necessary.

7. Are there any DIY tips for fixing the P0136 code in a 2005 Toyota Prius?

- While some repairs may require professional assistance, checking the sensor connections, inspecting for visible wiring damage, and clearing the code with an OBDII scanner can be DIY steps.

8. Is it necessary to reset the check engine light after fixing the P0136 code in a 2005 Toyota Prius?

- Yes, it is recommended to reset the check engine light using an OBDII scanner after fixing the issue to ensure the system recognizes that the fault has been addressed.

9. How serious is the HO2S12 circuit malfunction in a 2005 Toyota Prius?

- Ignoring the P0136 code can lead to reduced fuel efficiency, engine performance issues, and potential damage to other components, making it important to address the problem promptly.

10. Can a P0136 code in a 2005 Toyota Prius cause the vehicle to fail an emissions test?

- Yes, a P0136 code can cause the vehicle to fail an emissions test due to the impact on the exhaust gas monitoring system and increased emissions output.