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Engine-Codes – Generic – P0135

P0135 Code - O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1

Quick Answer

The O2 sensor, also known as the oxygen sensor, plays a crucial role in measuring the oxygen content in the exhaust gases of a vehicle. Common causes include Faulty O2 Sensor: The O2 sensor itself may be defective, causing the heater circuit to malfunction, Wiring Issues: Corrosion, damage, or poor connections in the wiring harness can disrupt the electrical signal to the O2 sensor heater, Blown Fuse: A blown fuse in the O2 sensor heater circuit can prevent the sensor from receiving power. 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
P0135 indicates O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1.
Common causes
Common causes include Faulty O2 Sensor: The O2 sensor itself may be defective, causing the heater circuit to malfunction, Wiring Issues: Corrosion, damage, or poor connections in the wiring harness can disrupt the electrical signal to the O2 sensor heater, Blown Fuse: A blown fuse in the O2 sensor heater circuit can prevent the sensor from receiving power.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P0135 Description

The O2 sensor, also known as the oxygen sensor, plays a crucial role in measuring the oxygen content in the exhaust gases of a vehicle. This information is essential for the engine control unit (ECU) to adjust the air-fuel mixture for optimal combustion. The P0135 trouble code specifically indicates a malfunction in the O2 sensor heater circuit of Bank 1 Sensor 1. Bank 1 refers to the side of the engine where cylinder 1 is located, while Sensor 1 indicates the sensor located before the catalytic converter.

OBDII Code P0135 - O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1
P0135 Code - O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1

Common Causes of P0135

  1. Faulty O2 Sensor: The O2 sensor itself may be defective, causing the heater circuit to malfunction.
  2. Wiring Issues: Corrosion, damage, or poor connections in the wiring harness can disrupt the electrical signal to the O2 sensor heater.
  3. Blown Fuse: A blown fuse in the O2 sensor heater circuit can prevent the sensor from receiving power.
  4. ECU Malfunction: A malfunctioning engine control unit may not be sending the correct signals to the O2 sensor heater circuit.

Symptoms of P0135

  1. Check Engine Light: The most obvious symptom of a P0135 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Poor Fuel Economy: A malfunctioning O2 sensor can lead to incorrect air-fuel mixture adjustments, resulting in reduced fuel efficiency.
  3. Rough Idle: An O2 sensor heater circuit malfunction can cause engine misfires, leading to a rough or unstable idle.
  4. Failed Emissions Test: If the O2 sensor is not functioning correctly, the vehicle may fail emissions tests due to increased emissions.
  5. Loss of Power: In severe cases, the vehicle may experience a loss of power or acceleration due to incorrect fueling.

How to Fix P0135

  1. Diagnostic Scan: Use an OBD-II scanner to retrieve the trouble code and determine if the issue is with the O2 sensor heater circuit.
  2. Check Wiring: Inspect the wiring harness for any damage, corrosion, or loose connections. Repair or replace as needed.
  3. Test O2 Sensor: Test the O2 sensor heater for continuity and proper function. Replace the sensor if it is faulty.
  4. Check Fuse: Verify that the fuse in the O2 sensor heater circuit is intact. Replace if necessary.
  5. Clear Codes: After completing the repairs, clear the trouble code and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0135

The cost of repairing a P0135 code can vary depending on the make and model of the vehicle, the location of the repair shop, and the specific cause of the issue. On average, the cost of replacing an O2 sensor heater circuit can range from $150 to $300 for parts and labor. Additional costs may apply if wiring repairs or an ECU diagnosis are needed. It's recommended to get a detailed quote from a trusted auto repair shop to determine the exact cost for your vehicle. Labor rates at auto repair shops typically range from $80 to $150 per hour, but rates can vary.

What does this mean?

Tech Notes for P0135

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The control module monitors how long it takes the sensor to warm up and start sending an adequate signal. The code is set when the sensor is taking too long to warm up. Water getting inside the heated oxygen sensor connector can cause the heated oxygen sensor fuse to blow. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors. If the fuse and connector are OK, replacing the O2 Sensor usually takes care of the problem.



























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Code P0135 Information for Specific Makes

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 P0135 Code

1. What does code P0135 mean?

Code P0135 indicates a malfunction in the oxygen (O2) sensor heater circuit for Bank 1 Sensor 1, which is responsible for heating the sensor to ensure accurate readings.

2. What are the symptoms of a P0135 code?

Common symptoms include an illuminated check engine light, decreased fuel efficiency, rough idling, and increased emissions.

3. What causes the P0135 code to appear?

The most common causes are a faulty O2 sensor, damaged wiring or connectors, a blown fuse, or a failing engine control module (ECM).

4. How do I diagnose the P0135 code?

Diagnose by inspecting the O2 sensor, checking the heater circuit’s wiring and connectors, testing for proper voltage, and verifying fuse integrity.

5. Can I drive with a P0135 code?

While the vehicle may still drive, ignoring the code can lead to poor fuel efficiency, higher emissions, and potential damage to other components.

6. How is a P0135 code fixed?

Repairs typically involve replacing the faulty O2 sensor, repairing damaged wiring, replacing a blown fuse, or addressing ECM-related issues.

7. How much does it cost to fix a P0135 code?

Repair costs vary but typically range from $150 to $400, depending on whether the sensor or wiring needs replacement.

8. What tools are needed to fix a P0135 code?

You’ll need an OBDII scanner, a multimeter, and potentially a wrench or socket set to replace the O2 sensor.

9. Can a bad O2 sensor cause other codes to appear?

Yes, a faulty O2 sensor can trigger additional codes related to fuel mixture, emissions, or catalytic converter efficiency.

10. What is Bank 1 Sensor 1?

Bank 1 Sensor 1 refers to the oxygen sensor located upstream (before the catalytic converter) on the side of the engine with cylinder 1.

Discuss the causes and fixes for P0135 OBDII Code

Submit a New Comment

  • I have a 2003 Toyota Avalon with about 35,000 miles on it. Recently, 3 lights went on: service engine soon (NOT flashing), VSC and TRAC. My trusted mechanic says that is caused by a bad oxygen sensor (P0135 B1, S1, HTR) that is seized in the exhaust manifold. His estimate to fix is quite expensive ($600 to $800) but he seems to think that the worst thing that could happen if not repaired is poor gas mileage.
    My concern by not fixing it is potential long term engine damage and damage to the catalytic converter. Who is more correct???
    Thank you very much for your feedback.

    Reply to Comment

  • Both are correct.
    $600 to $800 It's probably too high, but I do agree that a bad O2 will cause poor gas mileage.
    Poor reading from the O2 sensor may cause the engine to run too rich (too much gas) which may eventually damage the catalytic converter.
    In short term a bad O2 sensor will only cause poor gas mileage, but in a long term it may damage the catalytic converter.

    Reply to Comment