AutoCodes – Mercedes-Benz – P0136 Mercedes-Benz

P0136 Mercedes-Benz Code - O2 Sensor Circuit Malfunction Bank 1 Sensor 2

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 Mercedes-Benz indicates O2 Sensor Circuit Malfunction Bank 1 Sensor 2.
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 28,856

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 Mercedes-Benz 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 Mercedes-Benz - O2 Sensor Circuit Malfunction Bank 1 Sensor 2 - AutoCodes.com — P0136 Mercedes-Benz Code - O2 Sensor Circuit Malfunction Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0136 Mercedes-Benz?

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 Mercedes-Benz?

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 Mercedes-Benz 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 Mercedes-Benz code?

Need more information on how to fix the P0136 Mercedes-Benz code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0136 Mercedes-Benz 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 P0136 Mercedes-Benz Code

1. What are the common symptoms of OBDII code P0136 (O2 Sensor Circuit Malfunction Bank 1 Sensor 2) in a Mercedes-Benz?

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

2. What does the O2 Sensor Bank 1 Sensor 2 do in a Mercedes-Benz?

- Bank 1 Sensor 2 is the downstream oxygen sensor located after the catalytic converter. It monitors the efficiency of the catalytic converter and helps adjust fuel mixture for optimal performance.

3. What are the possible causes of OBDII code P0136 in a Mercedes-Benz?

- The code P0136 can be triggered by a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks, or issues with the engine's computer (ECU).

4. How can I diagnose the O2 Sensor Circuit Malfunction in my Mercedes-Benz?

- Diagnosing P0136 involves using an OBDII scanner to read the code, checking the oxygen sensor's wiring and connections, inspecting for exhaust leaks, and testing the sensor's voltage output.

5. Can I drive my Mercedes-Benz with OBDII code P0136?

- It is generally safe to drive with P0136, but prolonged driving with a faulty oxygen sensor can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How can I repair OBDII code P0136 in my Mercedes-Benz?

- Repair options include replacing the Bank 1 Sensor 2 oxygen sensor, repairing damaged wiring or connectors, fixing exhaust leaks, or resetting the ECU.

7. What are the long-term effects of ignoring OBDII code P0136 in a Mercedes-Benz?

- Ignoring P0136 can lead to decreased fuel efficiency, engine performance issues, and potential damage to the catalytic converter, resulting in costly repairs down the line.

8. Will resetting the Check Engine Light resolve OBDII code P0136 in my Mercedes-Benz?

- Simply resetting the Check Engine Light will not fix the underlying issue causing P0136. It is important to diagnose and repair the root cause of the code.

9. Can a DIY enthusiast repair OBDII code P0136 in a Mercedes-Benz?

- Depending on the DIYer's skill level and access to tools, replacing the oxygen sensor or repairing wiring/connectors can be done at home. However, diagnosing complex issues may require professional help.

10. How often should the oxygen sensors be replaced in a Mercedes-Benz to prevent O2 sensor circuit malfunctions?

- Oxygen sensors typically last around 100,000 miles but may need replacement earlier if symptoms of malfunction appear. Regular maintenance and monitoring can help prevent O2 sensor-related issues.