AutoCodes – Toyota – P0136 2009 Toyota Prius

P0136 2009 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 2009 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 4,313

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 2009 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 2009 Toyota Prius - HO2S12 Circuit Malfunction - AutoCodes.com — P0136 2009 Toyota Prius Code - HO2S12 Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0136 2009 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 2009 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 2009 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 2009 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 2009 Toyota Prius Code

1. What does the OBDII code P0136 mean for a 2009 Toyota Prius?

The code P0136 for a 2009 Toyota Prius indicates a malfunction in the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit.

2. What are common symptoms of the HO2S12 circuit malfunction in a 2009 Toyota Prius?

Common symptoms of the P0136 code in a 2009 Toyota Prius may include poor fuel economy, rough idling, hesitation during acceleration, and an illuminated check engine light.

3. What could cause the HO2S12 circuit malfunction in a 2009 Toyota Prius?

Possible causes of the P0136 code in a 2009 Toyota Prius include a faulty oxygen sensor, damaged wiring or connectors in the sensor circuit, exhaust leaks, or issues with the engine's air-fuel mixture.

4. How can I diagnose the HO2S12 circuit malfunction in my 2009 Toyota Prius?

To diagnose the P0136 code in a 2009 Toyota Prius, you can use an OBDII scanner to read the code, inspect the wiring and connectors of the oxygen sensor, check for exhaust leaks, and perform a voltage test on the sensor.

5. What are the repair options for the HO2S12 circuit malfunction in a 2009 Toyota Prius?

Repair options for the P0136 code in a 2009 Toyota Prius may include replacing the oxygen sensor, repairing or replacing damaged wiring or connectors, fixing any exhaust leaks, and ensuring the engine's air-fuel mixture is within specifications.

6. Can I drive my 2009 Toyota Prius with the P0136 code?

It is not recommended to drive your 2009 Toyota Prius with the P0136 code for an extended period as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

7. How much does it cost to fix the HO2S12 circuit malfunction in a 2009 Toyota Prius?

The cost to fix the P0136 code in a 2009 Toyota Prius can vary depending on the specific issue causing the malfunction. Repairs may range from $100 to $500 or more, including parts and labor.

8. Can I reset the check engine light after fixing the P0136 code in my 2009 Toyota Prius?

After fixing the P0136 code in a 2009 Toyota Prius, you can reset the check engine light using an OBDII scanner or by disconnecting the car's battery for a few minutes. If the issue is resolved, the light should stay off.

9. How often does the HO2S12 circuit malfunction occur in a 2009 Toyota Prius?

The HO2S12 circuit malfunction with the P0136 code can occur sporadically in a 2009 Toyota Prius due to various factors such as age, mileage, and driving conditions.

10. Is the HO2S12 circuit malfunction covered under warranty for a 2009 Toyota Prius?

Depending on the warranty status of your 2009 Toyota Prius, the repair for the P0136 code related to the HO2S12 circuit malfunction may be covered under certain warranties, such as the emissions control warranty.