AutoCodes – Toyota – P0136 2004 Toyota Prius

P0136 2004 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 2004 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 3,437

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 2004 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 2004 Toyota Prius - HO2S12 Circuit Malfunction - AutoCodes.com — P0136 2004 Toyota Prius Code - HO2S12 Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0136 2004 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 2004 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 2004 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.

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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 2004 Toyota Prius Code

1. What does the OBDII code P0136 on a 2004 Toyota Prius mean?

The code P0136 for a 2004 Toyota Prius indicates a malfunction in the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit.

2. What are the common symptoms of a P0136 code in a 2004 Toyota Prius?

Common symptoms of a P0136 code in a 2004 Toyota Prius may include poor fuel economy, rough idling, stalling, or a noticeable decrease in engine performance.

3. What are the possible causes of a P0136 code in a 2004 Toyota Prius?

Possible causes of a P0136 code in a 2004 Toyota Prius include a faulty oxygen sensor, damaged wiring or connectors in the sensor circuit, or an exhaust leak near the sensor.

4. How can I diagnose a P0136 code in a 2004 Toyota Prius?

To diagnose a P0136 code in a 2004 Toyota Prius, you can start by visually inspecting the oxygen sensor and its wiring for any signs of damage. Using an OBDII scanner to monitor the sensor's readings can also help pinpoint the issue.

5. Can I continue driving my 2004 Toyota Prius with a P0136 code?

While it may be possible to continue driving your 2004 Toyota Prius with a P0136 code, it is not recommended as it can lead to decreased fuel efficiency and potential damage to other engine components.

6. How do I repair a P0136 code in a 2004 Toyota Prius?

Repairing a P0136 code in a 2004 Toyota Prius typically involves replacing the HO2S12 sensor, checking and repairing any damaged wiring or connectors, and clearing the code with an OBDII scanner.

7. Are there any DIY tips for fixing a P0136 code in a 2004 Toyota Prius?

If you have experience working on cars, you may be able to replace the HO2S12 sensor yourself using basic tools. However, it's recommended to consult a professional mechanic for accurate diagnosis and repair.

8. How much does it cost to fix a P0136 code in a 2004 Toyota Prius?

The cost of fixing a P0136 code in a 2004 Toyota Prius can vary depending on the root cause of the issue and whether you choose to do the repair yourself or take it to a mechanic. It's advisable to get a few quotes for the repair.

9. Can a P0136 code in a 2004 Toyota Prius cause other problems if left unresolved?

If left unresolved, a P0136 code in a 2004 Toyota Prius can potentially lead to decreased fuel efficiency, increased emissions, and further damage to the engine or catalytic converter.

10. How often should the oxygen sensors be inspected in a 2004 Toyota Prius to prevent a P0136 code?

It's recommended to have the oxygen sensors inspected during regular maintenance intervals or whenever you notice any symptoms of a malfunction, to prevent the occurrence of a P0136 code in a 2004 Toyota Prius.