how to fix P0135 oxygen sensor issue in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before proceeding with repairs.

2. Remove the Oxygen Sensor

• Locate the upstream oxygen sensor (usually found near the exhaust manifold).
• Use a 22mm oxygen sensor socket to carefully unscrew the sensor from the exhaust pipe.
• Disconnect the electrical connector from the oxygen sensor.

3. Inspect and Clean

• Examine the oxygen sensor connector for any signs of corrosion or damage.
• If corrosion is present, clean the terminals with electrical contact cleaner.
• Inspect the wiring harness for any frays or shorts and repair as necessary.

4. Replace the Oxygen Sensor (if necessary)

• If the sensor is faulty, install a new oxygen sensor.
  1. Apply anti-seize compound to the threads of the new oxygen sensor (avoid getting it on the sensor tip).
  2. Screw the new sensor into the exhaust pipe and tighten to the manufacturer's specification (typically around 30 ft-lbs).
• Reconnect the electrical connector to the new oxygen sensor.

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0135 code from the vehicle's computer.