how to replace the spark plugs in Toyota Highlander Third Generation (2014-2019)

Toyota Highlander Third Generation (2014-2019)

Error Codes

1-2 hours

Time

medium

Difficulty

medium

Severity

3 min read

577 words

Problem Statement

Step-by-step guide to replace spark plugs in a 2014-2019 Toyota Highlander. Learn symptoms, diagnostic steps, and tools required for the job.

Affected Component

Engine

Estimated Time

1-2 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the negative battery terminal to prevent electrical shorts.
•Allow the engine to cool before starting work.

Symptoms

•Engine misfire or rough idle
•Poor acceleration or power loss
•Decreased fuel efficiency
•Illuminated check engine light
•Increased emissions

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify any related issues.
2
Inspect the spark plug wires or ignition coils for any visible damage or corrosion.
3
Check the condition of the current spark plugs by removing them and examining for wear, deposits, or damage.

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

•Socket set (10mm and 12mm sockets)
•Spark plug socket (usually 5/8 inch)
•Torque wrench
•Ratchet
•Extension bar
•Pliers
•Dielectric grease

Parts Required

•New spark plugs (OEM recommended)
•Ignition coil (if worn or damaged)

Related Faults

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Solution

1. Preparation

Tools Required:
- Socket set (10mm and 12mm sockets)
- Spark plug socket (usually 5/8 inch)
- Torque wrench
- Ratchet
- Extension bar
- Pliers
- Dielectric grease
Safety Warnings:
- Disconnect the negative battery terminal to prevent electrical shorts.
- Allow the engine to cool before starting work.

2. Remove Engine Covers (if applicable)

Remove any plastic engine covers by unscrewing the bolts (usually 10mm).
Set aside the covers in a safe place.

3. Access Spark Plugs

Locate the ignition coils on top of each spark plug.
Disconnect the electrical connectors from the ignition coils by pressing the tab and pulling them off.
Remove the bolts securing the ignition coils using a 10mm socket.
Gently pull the ignition coils out to expose the spark plugs.

4. Remove Old Spark Plugs

Use a spark plug socket and ratchet to carefully unscrew each spark plug from the cylinder head.
Inspect the removed spark plugs for wear and carbon buildup.

5. Install New Spark Plugs

Apply a small amount of anti-seize compound to the threads of the new spark plugs to prevent sticking.
Hand-tighten the new spark plugs into the cylinder head.
Use a torque wrench to tighten the spark plugs to the manufacturer’s specification (usually around 13-15 ft-lbs).

6. Reinstall Ignition Coils

Apply a small amount of dielectric grease to the inside of each ignition coil boot.
Insert the ignition coils back into place and secure them with the bolts.
Reconnect the electrical connectors to the ignition coils.

7. Reinstall Engine Covers

Place the engine covers back in position and secure them with the bolts removed earlier.

8. Reconnect Battery

Reconnect the negative battery terminal and ensure it is secure.