P0135 Honda: Troubleshooting and Fixing Oxygen Sensor Error

If you own a Honda vehicle and have come across the P0135 error code, don’t worry! This article will guide you through the process of troubleshooting and fixing this common issue. The P0135 error code is related to the oxygen sensor, an important component of the engine management system. By following the steps outlined below, you can resolve the P0135 error code and ensure the smooth operation of your Honda.

Understanding the P0135 Error Code

The P0135 error code indicates a malfunction or potential problem with the oxygen sensor’s heater circuit in bank 1, sensor 1. The oxygen sensor plays a crucial role in monitoring the air-fuel ratio in the exhaust gases. When this code appears, it typically means that the oxygen sensor is not heating up properly. This error code is frequently encountered in Honda Civic, Accord, and CR-V models, among others.

Common Symptoms of the P0135 Error Code

If your Honda vehicle is experiencing the P0135 error code, you may notice the following symptoms:

  1. Illuminated Check Engine Light: The most obvious sign of the P0135 error code is the illumination of the Check Engine Light on your vehicle’s dashboard.
  2. Decreased Fuel Efficiency: A faulty oxygen sensor can lead to an improper fuel-air mixture, resulting in decreased fuel efficiency.
  3. Rough Idling: The engine may idle roughly or experience hesitation during acceleration due to incorrect feedback from the oxygen sensor.
  4. Engine Misfires: In some cases, the P0135 error code can lead to engine misfires, causing your Honda to run unevenly or shake.

Troubleshooting the P0135 Error Code

Now, let’s dive into the troubleshooting process for the P0135 error code. By following these steps, you can identify and resolve the underlying issue:

Step 1: Checking the Oxygen Sensor Wiring

Start by inspecting the wiring harness connected to the oxygen sensor. Look for any visible damage, corrosion, or loose connections. Ensure that the wiring is securely connected and properly seated. To be thorough, use a multimeter to check for continuity in the sensor’s wiring.

Step 2: Inspecting the Oxygen Sensor Connector

Disconnect the oxygen sensor connector and carefully examine it for any signs of damage, corrosion, or loose pins. If you notice any issues, clean the connector and ensure a tight connection during reinstallation.

Step 3: Testing the Oxygen Sensor Voltage

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Connect the positive lead of a digital multimeter to the oxygen sensor’s signal wire and the negative lead to a suitable ground. Start the engine and measure the voltage output of the oxygen sensor. Compare the measured voltage with the manufacturer’s specifications to determine if the sensor is functioning correctly.

Step 4: Verifying the Oxygen Sensor Heater Circuit

Use a digital multimeter to test the resistance of the oxygen sensor’s heater circuit. Compare the resistance reading with the manufacturer’s specifications. If the resistance is out of the acceptable range, it indicates a faulty sensor that needs to be replaced.

Step 5: Checking for Exhaust Leaks

Inspect the exhaust system for leaks, such as cracks or holes in the pipes or muffler. Even small leaks can affect the oxygen sensor’s readings. Use a suitable method, such as a smoke machine or soapy water, to identify any leaks. Repair or replace the damaged components as necessary.

Step 6: Diagnosing the Engine Control Module (ECM)

Utilize an OBD-II scanner to retrieve and analyze additional error codes that may be stored in the ECM. Inspect the ECM for signs of damage or water intrusion. For further diagnostics related to the ECM, consult the vehicle’s service manual or seek professional assistance.

Fixing the P0135 Error Code

Once you have identified the root cause of the P0135 error code, it’s time to fix the issue. Here are the steps to follow:

Step 1: Replacing a Faulty Oxygen Sensor

Purchase a compatible replacement oxygen sensor for your Honda vehicle. Disconnect the negative battery terminal and remove the old sensor. Install the new oxygen sensor and reconnect any necessary wiring. Reconnect the negative battery terminal and clear the error codes.

Step 2: Repairing Damaged Wiring or Connectors

If you found any damaged wiring or connectors during the troubleshooting process, repair or replace them as needed. Ensure proper insulation and secure connections to guarantee reliable operation.

Step 3: Resolving Issues with the Oxygen Sensor Heater Circuit

If the resistance of the heater circuit was out of range during testing, replace the oxygen sensor. Ensure that the new sensor’s heater circuit is functioning correctly to maintain optimal performance.

Step 4: Fixing Exhaust Leaks

Repair or replace any components of the exhaust system that were found to be leaking. Use appropriate methods or materials to seal the leaks effectively and prevent future issues.

Step 5: Resetting the ECM and Retesting

Use an OBD-II scanner to clear the error codes stored in the ECM. Start the engine and monitor for any recurrence of the P0135 error code. Retest the oxygen sensor’s voltage to ensure it falls within the specified range.


What does the P0135 error code in Honda vehicles indicate?

The P0135 error code signifies a malfunction or potential problem with the oxygen sensor’s heater circuit in bank 1, sensor 1. It indicates that the oxygen sensor is not heating up properly.

Which Honda vehicles are commonly affected by the P0135 error code?

The P0135 error code can be encountered in various Honda models, including Civic, Accord, CR-V, and others.

What are the common symptoms of the P0135 error code?

Common symptoms include an illuminated Check Engine Light, decreased fuel efficiency, rough idling, and engine misfires.

Can I drive my Honda vehicle with the P0135 error code?

It is generally safe to drive your Honda vehicle with the P0135 error code, but it is recommended to have it diagnosed and repaired as soon as possible to avoid potential engine performance issues.

What should I do if I find a fault in the oxygen sensor wiring or connector?

If you find any damage, corrosion, or loose connections in the oxygen sensor wiring or connector, you should repair or replace them as needed. Ensure secure connections and proper insulation.

Can I replace the oxygen sensor myself?

If you have experience and the necessary tools, you can replace the oxygen sensor yourself. However, if you’re unsure or uncomfortable with the process, it’s recommended to seek professional assistance.

How do I clear the P0135 error code after fixing the issue?

Use an OBD-II scanner to clear the error codes stored in the ECM. This will reset the system and allow you to monitor if the P0135 error code reappears.

Are there any precautions to take while fixing the P0135 error code?

When working on your vehicle, ensure the engine is cool, disconnect the battery’s negative terminal, and follow safety precautions outlined in the vehicle’s service manual.

What if I am unable to resolve the P0135 error code on my own?

If you are unable to troubleshoot or fix the P0135 error code, it’s recommended to seek professional assistance from a qualified mechanic or a Honda dealership. They have the expertise and tools to diagnose and resolve the issue effectively.


Resolving the P0135 error code in your Honda vehicle is achievable by following the step-by-step troubleshooting and fixing process outlined in this guide. It’s important to diagnose and repair the issue promptly to maintain optimal performance and fuel efficiency. However, if you are unsure or encounter challenges during the process, it is advisable to seek professional assistance from a qualified mechanic or a Honda dealership. Remember, timely diagnosis and repair will keep your Honda running smoothly on the road.

Note: The information provided in this article is intended for informational purposes only. Always refer to the vehicle’s service manual and consult with a qualified automotive technician for accurate diagnosis and repair guidance.