Learn to change the spark plugs on a Mazda with a four-cylinder engine.
These instructions apply to many models, including Mazda 2, 3, 5, 6, 323, CX-5, CX-7, CX-9, CX-50, etc. Replacing spark plugs on a Mazda engine requires a few essential tools and two hours of labor.
- Check Engine Light On
- Poor Engine Performance
- Decrease in MPG
- Engine idles roughly
- Mazda engine misfires
- Hesitation during acceleration
- Fault Codes for cylinder misfires include P0300, P0301, P0302, P0303, and P0304.
What you will need
Replacing the spark plugs on a Mazda requires a few essential tools and parts.
Access Factory Repair Manuals
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- Spark Plug Socket
- 4-inch extension
- 3/8 Ratched
- 10mm socket
- Mazda Spark Plugs
The two options we would recommend are:
- NGK Iridium Spark Plugs. If you are looking for the best aftermarket spark plugs for Mazda, a good choice is NGK Spark Plugs for Mazda. They come pre-gapped for Mazda and also have excellent reviews from Mazda owners.
- OEM Mazda Spark Plugs
OEM Mazda sparks plug at the dealer cost over $20 per spark plug. If you prefer OEM spark plugs, buy them online to save money.
The following instructions show you how to change spark plugs on a Mazda four-cylinder engine. This is one of the most common Mazda engines on Mazda 3, Mazda 5, Mazda 6, CX-5, and CX-7.
Park vehicle. Park your Mazda on level ground. Allow the engine to cool down.
- Pull the hood release and open the hood.
- Disconnect the negative battery terminal. The negative terminal is difficult to reach due to the small space between the battery and the firewall.
- Remove the engine cover. Check for bolts on top of the engine cover. If no bolts are present, lift the engine cover with both hands. In this Mazda, there are no screws to secure the cover. Only tabs underneath the engine cover.
- Unplug the electrical connector from the ignition coil. Press on the trim tab, then pull. Do this for all four coils.
- Remove the 10mm bolts that secure the coil in place. Pull the coils out.
- Remove Spark Plugs. Use the spark plug socket, extension, and ratchet to remove the spark plugs from your Mazda.
- Use a magnetic pickup tool to pull out the spark plugs.
- Install new spark plugs. Install new spark plugs on your Mazda.
- Tighten the spark plug finger-tight until it reaches the cylinder head.
- Torque the spark plugs to 20 ft. lb. Verify the torque value for your engine.
- Reinstall Ignition Coils. Tighten the ignition coil bolt’s hand tight.
- Reinstall the coils and connect the electrical connectors.
- Reinstall the engine cover.
- Start the vehicle and ensure it is running correctly. The check engine light should stay off. If the check engine light comes on, follow this guide on troubleshooting the Mazda check engine light.
Replacing the spark plugs on a Mazda is a straightforward procedure that can save you hundreds of dollars.
Mazda Spark Plug Replacement Interval
The recommended interval spark plug replacement for most Mazda vehicles with a four-cylinder engine is every 75,000 miles. This value can vary depending on the spark plug type installed in the engine. Check the owner’s manual to verify.
Copper spark plugs on older Mazda vehicles must be replaced every 30,000 miles.
Tighten the spark plug to:
- 15 lb. ft. – 14mm spark plugs.
- 20 lb. ft. – 18mm spark plugs.
Spark Plug Gap
Mazda factory spark plug gap is typically in the .045 to .057 range. Iridium spark plugs such as Denso Iridiums for Mazda come pre-gapped at 0.044 and should not be changed. NGK Spark Plugs for Mazda come pre-gapped at 0.054. Do not gap iridium spark plugs.
Check Engine Light Still On
If you need to reset the check engine light of your Mazda after replacing the spark plugs, use the YOUCANIC Full System Scanner to clear the code and remove the check engine light on your Mazda dashboard. This scanner also can read every control module of your vehicle.
We hope you find the Mazda 4 Cylinder Engine Spark Pug Replacement guide helpful. Check these troubleshooting and repair guides for more help on your Mazda.