What are the symptoms of a bad spark plug in a 2021 Ford Explorer?

Ford Explorer Sixth Generation (2020-present)

Error Codes

1-2 hours

Time

medium

Difficulty

medium

Severity

4 min read

798 words

Problem Statement

Learn about the symptoms of bad spark plugs in a 2021 Ford Explorer and follow diagnostic steps to identify and replace faulty spark plugs.

Affected Component

spark plug

Estimated Time

1-2 hours

Symptoms

•Engine Misfire
•Reduced Fuel Efficiency
•Difficulty Starting
•Rough Idle
•Loss of Power
•Check Engine Light
•Increased Emissions

Diagnostic Steps

1
Connect OBD-II Scanner and retrieve codes
2
Inspect spark plugs for wear
3
Check wiring and connectors
4
Remove spark plug and check resistance
5
Perform compression test (optional)

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
•Torque Wrench
•Spark Plug Socket
•Extension Bar
•Ratchet
•Dielectric Grease
•Compressed Air (optional)
•Multimeter

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Solution

Tools Required

OBD-II Scanner
Torque Wrench
Spark Plug Socket (usually 5/8 inch)
Extension Bar
Ratchet
Dielectric Grease
Compressed Air (optional)
Multimeter (for checking spark plug resistance)

Step 1: Check Engine Light Diagnosis

Connect OBD-II Scanner: Plug the scanner into the OBD-II port under the dashboard.
Retrieve Codes: Read diagnostic trouble codes (DTCs). Look for codes related to misfires (e.g., P0300-P0306).
Interpret Codes: Make a note of any codes that may indicate a specific cylinder misfire or ignition issue.

Step 2: Visual Inspection

Inspect Spark Plugs: Remove the ignition coil cover (if applicable) and visually inspect the spark plugs for any signs of wear, such as:
- Cracks or chips in the ceramic insulator
- Oil or carbon buildup
- Burn marks or excessive wear
Check Wiring and Connectors: Inspect the wiring and connectors leading to the spark plugs for any signs of damage or corrosion.

Step 3: Spark Plug Resistance Check

Remove Spark Plug: Carefully remove the spark plug using a spark plug socket and ratchet.
Check Resistance: Use a multimeter to check the resistance of the spark plug. A typical resistance reading for a spark plug should be less than 10,000 ohms. If it’s significantly higher, consider replacing the spark plug.

Step 4: Perform Compression Test (Optional)

Remove All Spark Plugs: For a more thorough diagnosis, remove all spark plugs.
Attach Compression Tester: Screw the compression tester into the spark plug hole of the cylinder in question.
Crank the Engine: Perform a compression test by cranking the engine several times and recording the pressure readings.
Compare Readings: Check that all cylinder readings are within manufacturer specifications.

Repair Instructions

If diagnostics indicate that the spark plugs are indeed faulty, follow these steps for replacement:

Tools Required

New Spark Plugs (OEM recommended)
Torque Wrench
Spark Plug Socket
Extension Bar
Ratchet
Dielectric Grease

Step 1: Gather New Spark Plugs

Purchase Quality Spark Plugs: Ensure you have the correct OEM spark plugs for your 2021 Ford Explorer.

Step 2: Prepare the Engine

Disconnect Battery: Disconnect the negative terminal of the battery to ensure safety during the replacement process.
Remove Engine Covers: If applicable, remove any plastic engine covers to access the ignition coils and spark plugs.

Step 3: Replace Spark Plugs

Remove Ignition Coils: Unplug the electrical connectors from each ignition coil. Remove the bolts holding the coils in place and lift them out.
Clean Spark Plug Wells: Use compressed air to blow out any debris from the spark plug wells to prevent contamination.
Install New Spark Plugs:
- Apply a small amount of dielectric grease to the threads of the new spark plugs to prevent seizing and ensure proper installation.
- Hand-tighten the new spark plugs into the cylinder head.
Torque Spark Plugs: Use a torque wrench to tighten the spark plugs to the manufacturer’s specifications (typically around 13-16 ft-lbs, but check your service manual).
Reinstall Ignition Coils: Replace the ignition coils, ensuring that they are properly seated and secured with bolts.

Step 4: Reassemble and Test

Reconnect Battery: Reconnect the negative terminal of the battery.
Start Engine: Start the engine to ensure it runs smoothly and the symptoms have been resolved.
Check for Codes: Use the OBD-II scanner again to ensure no new codes appear.

By following these steps, you should successfully diagnose and repair any issues related to faulty spark plugs in your 2021 Ford Explorer.