P0135 Fault Code

O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0135 code indicates a malfunction in the O2 sensor heater circuit for Bank 2 Sensor 1. This sensor is crucial for monitoring the exhaust gases and ensuring the engine runs efficiently. If this circuit fails, it can lead to poor engine performance and increased emissions.

• O2 Sensor: Measures the oxygen level in the exhaust gases.
• Heater Circuit: Ensures the sensor reaches its optimal operating temperature quickly for accurate readings.
• Bank 2: Refers to the side of the engine opposite to Bank 1, which typically contains cylinder 1.
• Sensor 1: The first O2 sensor located before the catalytic converter.

What are the symptoms of the P0135 code?

When the P0135 code is present, you may notice:

• Check Engine Light: The warning light may illuminate on your dashboard.
• Poor Fuel Economy: Increased fuel consumption due to inefficiencies in the fuel mixture.
• Decreased Performance: Hesitation or reduced power during acceleration.
• Rough Idle: The engine may run unevenly, especially when cold.

What causes the P0135 code?

The malfunction can be caused by a variety of issues, including:

• Open Circuit: Broken wires or poor connections in the heater circuit.
• Short Circuit: Wires that are incorrectly connected can cause overheating and failure.
• Faulty Sensor: The O2 sensor itself may have failed, leading to inaccurate readings.
• Fuses: Blown fuses related to the sensor circuit can interrupt power supply to the heater.

How to fix P0135?

To resolve the P0135 code, the following steps are recommended:

• Inspect Wiring and Connectors: Check for any visible damage or disconnections in the heater circuit wiring.
• Test the O2 Sensor: Use a multimeter to check the functionality of the sensor and its heater.
• Repair or Replace Faulty Components: If any wiring is damaged or the sensor is faulty, replace those components.
• Check Fuses: Ensure all related fuses are intact and functioning properly.
• Clear the Code: After repairs, clear the error code using a scan tool and test drive the vehicle.