why does my Toyota Highlander Third Generation (2014-2019) check engine light keep coming on

Toyota Highlander Third Generation (2014-2019)

Error Codes

1-3 hours

Time

medium

Difficulty

medium

Severity

3 min read

537 words

Problem Statement

Learn how to diagnose and fix the check engine light issue in a 2014-2019 Toyota Highlander. Step-by-step guide with diagnostic steps and repair instructions.

Affected Component

Engine

Estimated Time

1-3 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.

Symptoms

•Check Engine Light illuminated
•Engine running rough or misfiring
•Decreased fuel efficiency
•Unusual engine noises (e.g., knocking or pinging)
•Emission-related issues (e.g., increased exhaust smoke)
•Vehicle may enter limp mode (reduced power)

Diagnostic Steps

1
Scan the vehicle's OBD-II system using a scanner to retrieve error codes.
2
Review the error codes and note any related to emissions, fuel system, or ignition system.
3
Inspect the gas cap for proper seal and condition; replace if damaged.
4
Check the engine oil level and condition; ensure it is within specifications.
5
Inspect air intake and vacuum hoses for leaks or damage.
6
Test the ignition components (spark plugs, coils) for wear or failure.
7
Conduct a visual inspection of the exhaust system for leaks or blockages.

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
•Socket set
•Torque wrench
•Multimeter
•Vacuum gauge

Parts Required

•Ignition coils (if faulty)
•Spark plugs (if worn)
•Vacuum hoses (if damaged)

Related Faults

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Diagnostic Steps

1
Scan the vehicle's OBD-II system using a scanner to retrieve error codes.
2
Review the error codes and note any related to emissions, fuel system, or ignition system.
3
Inspect the gas cap for proper seal and condition; replace if damaged.
4
Check the engine oil level and condition; ensure it is within specifications.
5
Inspect air intake and vacuum hoses for leaks or damage.
6
Test the ignition components (spark plugs, coils) for wear or failure.
7
Conduct a visual inspection of the exhaust system for leaks or blockages.

Solution

1. Preparation

Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, vacuum gauge.
Safety Warnings: Disconnect the battery before working on electrical systems.

2. Address Fault Codes

Use the OBD-II scanner to clear the fault codes after repairs are completed.
If the same code returns, focus on the specific area indicated by the code.

3. Replace Faulty Components

If the issue is determined to be a faulty ignition coil:
- Sub-steps:
  1. Remove the engine cover (if applicable) using a socket set.
  2. Disconnect the electrical connector from the ignition coil.
  3. Remove the ignition coil bolt and take out the coil.
  4. Install a new ignition coil and secure it with the bolt.
  5. Reconnect the electrical connector.
If the issue is with the spark plugs:
- Sub-steps:
  1. Remove the ignition coils as described above.
  2. Use a spark plug socket to remove the old spark plugs.
  3. Install new spark plugs, tightening to the manufacturer's specified torque.
  4. Reinstall the ignition coils.

4. Inspect and Repair Vacuum Leaks

If vacuum leaks are suspected:
- Sub-steps:
  1. Use a vacuum gauge to check the intake system for leaks.
  2. Repair or replace any damaged hoses or gaskets.
  3. Ensure all connections are tight and secure.

5. Final Inspection

Conduct a road test to ensure the CEL does not return and the vehicle operates normally.