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What error codes are frequently associated with the 2021 Toyota Highlander? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/What error codes are frequently associated with the 2021 Toyota Highlander?

What error codes are frequently associated with the 2021 Toyota Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
medium
Difficulty
medium
Severity
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
666 words

Problem Statement

Explore frequently associated error codes for the 2021 Toyota Highlander, including symptoms, potential causes, and diagnostic steps.

Affected Component
engine, transmission, emissions systems

Symptoms

  • •Check Engine Light (CEL) illuminated
  • •reduced fuel efficiency
  • •possible rough idle
  • •possible fuel odor
  • •loss of power
  • •shaking during acceleration
  • •stalling
  • •erratic transmission behavior
  • •harsh shifting
  • •slipping transmission
  • •poor fuel economy
  • •increased emissions

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

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
  • •Multimeter
  • •vacuum gauge
  • •smoke machine

Additional Information

Affected Component
engine, transmission, emissions systems
Difficulty
medium
Severity
medium
Tools Required
4 items

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Frequently Associated Error Codes with the 2021 Toyota Highlander

The 2021 Toyota Highlander, part of the fourth generation (XU70), can trigger various error codes related to its engine, transmission, emissions, and other systems. Below are some commonly reported error codes along with their meanings, symptoms, and potential causes:

Common Error Codes

  1. P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

    • Symptoms: Check Engine Light (CEL) illuminated, reduced fuel efficiency, possible rough idle.
    • Potential Causes: Faulty catalytic converter, oxygen sensor failure, exhaust leaks.

  2. P0456 - Evaporative Emission Control System Leak Detected (Very Small Leak)

    • Symptoms: CEL illuminated, possible fuel odor, reduced fuel efficiency.
    • Potential Causes: Loose or damaged gas cap, leak in EVAP system components, faulty purge valve.

  3. P0300 - Random/Multiple Cylinder Misfire Detected

    • Symptoms: Rough idle, loss of power, shaking during acceleration, CEL illuminated.
    • Potential Causes: Faulty spark plugs or ignition coils, fuel delivery issues, vacuum leaks.

  4. P0171 - System Too Lean (Bank 1)

    • Symptoms: CEL illuminated, rough idle, stalling, reduced power.
    • Potential Causes: Vacuum leaks, faulty mass air flow (MAF) sensor, fuel injector issues.

  5. P0717 - Input Speed Sensor Range/Performance Problem

    • Symptoms: CEL illuminated, erratic transmission behavior, harsh shifting, slipping transmission.
    • Potential Causes: Faulty input speed sensor, wiring issues, transmission control module (TCM) problems.

  6. P0138 - O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)

    • Symptoms: CEL illuminated, poor fuel economy, increased emissions.
    • Potential Causes: Faulty oxygen sensor, wiring issues, exhaust leaks.
Repair Instructions

Example Repair: P0420 - Catalyst System Efficiency Below Threshold

  1. Confirm the Code: Use the OBD-II scanner to confirm the P0420 code is present.

  2. Inspect the Exhaust System:

    • Check for any visible damage or leaks in the exhaust system before and after the catalytic converter.

  3. Test Oxygen Sensors:

    • Disconnect the upstream and downstream O2 sensors and check with a multimeter:
      • Upstream Sensor: Should fluctuate between 0.1V and 0.9V while the engine is running.
      • Downstream Sensor: Should remain relatively stable; if it fluctuates like the upstream, the catalytic converter may be failing.

  4. Check Catalytic Converter:

    • Perform a temperature test on the catalytic converter; the inlet should be significantly hotter than the outlet if the catalytic converter is functioning properly.

  5. Replace Faulty Parts:

    • If the catalytic converter is confirmed to be faulty, replace it. Ensure to use OEM or high-quality aftermarket parts.

  6. Reassemble and Test:

    • Reconnect all components, start the engine, and check for any exhaust leaks. Clear the code again and take the vehicle for a test drive to confirm the repair.
Final Note

If the error codes persist or if additional symptoms arise, it may be necessary to consult a professional technician for further diagnosis and repair. Regular maintenance and timely repairs can help prevent these issues from becoming more severe.