how to fix P0135 code in Toyota Highlander Third Generation (2014-2019)

Toyota Highlander Third Generation (2014-2019)

Error Codes

1-2 hours

Time

medium

Difficulty

high

Severity

Error Code: P0135

3 min read

509 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0135 oxygen sensor heater circuit issue in Toyota Highlander (2014-2019). Step-by-step guide with tools and procedures.

Error Code

P0135

Affected Component

Exhaust System

Estimated Time

1-2 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before working on the exhaust system to prevent burns.

Symptoms

•Check engine light illuminated
•Decreased fuel efficiency
•Rough idle
•Engine stalling
•Failed emissions test

Diagnostic Steps

1
Scan the vehicle's OBD-II system for error codes to confirm the P0135 code.
2
Visually inspect the wiring and connectors of the upstream oxygen sensor for damage or corrosion.
3
Measure the resistance of the oxygen sensor heater element using a multimeter to ensure it is within specification.
4
Check the voltage supply to the oxygen sensor heater circuit with a multimeter.
5
Inspect relevant fuses and relays related to the oxygen sensor heater circuit for continuity.
6
Perform a continuity test on the oxygen sensor wiring to ensure there are no breaks.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Oxygen sensor socket or wrench
•Multimeter
•Socket set
•Torque wrench

Parts Required

•Upstream oxygen sensor (Bank 1)

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Diagnostic Steps

1
Scan the vehicle's OBD-II system for error codes to confirm the P0135 code.
2
Visually inspect the wiring and connectors of the upstream oxygen sensor for damage or corrosion.
3
Measure the resistance of the oxygen sensor heater element using a multimeter to ensure it is within specification.
4
Check the voltage supply to the oxygen sensor heater circuit with a multimeter.
5
Inspect relevant fuses and relays related to the oxygen sensor heater circuit for continuity.
6
Perform a continuity test on the oxygen sensor wiring to ensure there are no breaks.

Solution

1. Preparation

Gather all necessary tools and parts.
Disconnect the negative terminal of the battery to ensure safety.
Raise the vehicle securely if access to the underside is needed.

2. Remove the Oxygen Sensor

Locate the upstream oxygen sensor (Bank 1) near the exhaust manifold.
Use an oxygen sensor socket or wrench to carefully unscrew the sensor from the exhaust pipe.
Disconnect the electrical connector from the oxygen sensor.

3. Inspect and Replace

Inspect: Check the old oxygen sensor for signs of physical damage, contamination, or excessive wear.
Replace: If the sensor is faulty, install the new oxygen sensor by threading it into the exhaust pipe and tightening it to the manufacturer’s specification (typically 30-50 ft-lbs).
Reconnect: Plug the electrical connector back into the new oxygen sensor.

4. Check Wiring and Connectors

Inspect the wiring harness leading to the oxygen sensor for any signs of fraying or damage.
If any issues are found, repair or replace the wiring as necessary to ensure proper connection.

5. Reconnect Battery and Test

Reconnect the negative battery terminal.
Start the engine and allow it to reach operating temperature to ensure the oxygen sensor is functioning.