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

Quick Answer

The P0135 diagnostic trouble code (DTC) for Hyundai vehicles indicates an issue with the O2 (oxygen) sensor heater circuit in Bank 1 Sensor 1. Common causes include Faulty O2 Sensor: The O2 sensor itself may be defective, causing the heater circuit malfunction, Wiring Issues: Damaged or corroded wiring connections to the O2 sensor can prevent proper heater circuit operation, ECM Malfunction: A problem with the engine control module (ECM) can also trigger the P0135 code. 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 Hyundai 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 malfunction, Wiring Issues: Damaged or corroded wiring connections to the O2 sensor can prevent proper heater circuit operation, ECM Malfunction: A problem with the engine control module (ECM) can also trigger the P0135 code.
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 Aug 18, 2024
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Code P0135 Hyundai Description

The P0135 diagnostic trouble code (DTC) for Hyundai vehicles indicates an issue with the O2 (oxygen) sensor heater circuit in Bank 1 Sensor 1. This sensor is responsible for monitoring the oxygen levels in the exhaust gases and sending this data to the engine control module (ECM) for proper air-fuel ratio adjustments. The heater circuit within the sensor is used to bring the sensor up to operating temperature quickly for accurate readings. When this circuit malfunctions, it can cause the O2 sensor to not function properly, leading to potential fuel efficiency issues, increased emissions, and overall poor engine performance.

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

Common Causes of P0135 Hyundai

  1. Faulty O2 Sensor: The O2 sensor itself may be defective, causing the heater circuit malfunction.
  2. Wiring Issues: Damaged or corroded wiring connections to the O2 sensor can prevent proper heater circuit operation.
  3. ECM Malfunction: A problem with the engine control module (ECM) can also trigger the P0135 code.
  4. Blown Fuse: A blown fuse in the O2 sensor heater circuit can lead to a malfunction.
  5. Environmental Factors: Exposure to extreme heat or moisture can also cause the O2 sensor heater circuit to fail.

Symptoms of P0135 Hyundai

  1. Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the dashboard.
  2. Poor Fuel Economy: A faulty O2 sensor heater circuit can result in incorrect air-fuel mixture readings, leading to decreased fuel efficiency.
  3. Rough Idling: The engine may experience rough idling or hesitation when the O2 sensor is not functioning correctly.
  4. Failed Emissions Test: If the O2 sensor heater circuit is malfunctioning, the vehicle may fail emissions tests due to increased emissions.
  5. Engine Misfires: In severe cases, the engine may experience misfires or lack of power due to improper air-fuel ratio adjustments.

How to Fix P0135 Hyundai

  1. Diagnose: Use a scan tool to verify the P0135 code and then inspect the O2 sensor and related components for any visible damage.
  2. Test O2 Sensor: Check the O2 sensor's heater circuit for continuity and resistance to determine if it is faulty.
  3. Check Wiring: Inspect the wiring harness for any breaks, corrosion, or damage, and repair or replace as needed.
  4. Replace O2 Sensor: If the O2 sensor itself is faulty, replace it with a new sensor compatible with your Hyundai model.
  5. Clear Codes: After performing the repair, clear the diagnostic trouble codes with a scan tool and test drive the vehicle to ensure the issue is resolved.

Cost to Fix P0135 Hyundai

The typical cost to repair a P0135 O2 Sensor Heater Circuit Malfunction in a Hyundai can range from $150 to $400, including parts and labor. Keep in mind that the final cost may vary depending on the specific model of your Hyundai, the location of the repair shop, and any additional repairs or diagnostic work required. It's recommended to obtain quotes from multiple repair shops to compare prices and ensure a fair estimate.

What does this mean?

Tech Notes for P0135 Hyundai

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 triggered 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 sensor and connector are OK, replacing the O2 Sensor 1 usually takes care of the problem.





User Submitted Video

When is the Code Detected?

Current amperage in the front heated oxygen sensor heater circuit is out of the normal range. (An improper voltage drop signal is sent to ECM through the front heated oxygen sensor heat

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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 P0135 Hyundai Code

What does the OBD-II code P0135 mean on a Hyundai?

Code P0135 indicates a malfunction in the oxygen sensor heater circuit for Bank 1 Sensor 1, which monitors the air-fuel mixture in the exhaust.

What are the symptoms of code P0135 in a Hyundai?

Symptoms may include the check engine light turning on, increased fuel consumption, poor engine performance, or failed emissions tests.

What causes the P0135 code in a Hyundai?

Common causes include a faulty oxygen sensor, damaged wiring or connectors, a blown fuse, or issues with the engine control module (ECM).

Can I drive my Hyundai with the P0135 code?

While it may be safe to drive for a short time, ignoring the issue can lead to reduced fuel efficiency and potential damage to the catalytic converter.

How do I diagnose the P0135 code in a Hyundai?

Start by inspecting the oxygen sensor wiring and connectors for damage, checking fuses, and testing the oxygen sensor heater circuit with a multimeter.

How is the P0135 code fixed in a Hyundai?

Repairs typically involve replacing the faulty oxygen sensor, repairing damaged wiring, or addressing issues with the ECM or related circuits.

How much does it cost to fix the P0135 code in a Hyundai?

Repair costs can range from $150 to $400, depending on whether the oxygen sensor needs replacement or if additional wiring repairs are required.

Which oxygen sensor does the P0135 code refer to?

The code refers to Bank 1 Sensor 1, which is the oxygen sensor located upstream (before the catalytic converter) on the engine's first bank.

Can a dirty air filter cause the P0135 code in a Hyundai?

No, a dirty air filter is unlikely to cause this code, as it specifically relates to the oxygen sensor heater circuit.

How do I prevent the P0135 code from recurring in my Hyundai?

Regular maintenance, such as inspecting and replacing oxygen sensors at recommended intervals and ensuring wiring is intact, can help prevent this issue.

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