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NA Miata Spark Plug Replacement
NA Miata Spark Plug Replacement: Spark Plugs are one of the most important maintenance items to replace on your Miata. Replacing you NA Miata Spark Plug is very easy, and can help cure misfire problems. If your car has the check engine light on for a misfire code (P0301, P0302, P0303, P0304, P0300) replacing your spark plugs should be one of the first items to address.
Mazda recommends that you replace your spark plugs every 30,000 miles or 24 months, whichever comes first. For a full list of OEM-specified maintenance intervals, download our free NA Miata maintenance checklist here.
It is also recommended to replace your spark plug wires at the same time.
| Estimated Mechanic Cost (Parts + Labor) | Parts Cost | DIY Savings |
| $275 | $25 | $250 |
Tools Required:
- 3/8 ratchet with extension
- 5/8 Spark Plug Socket
- Spark Plug Gap Tool
Parts Required:
Instructions:
- Remove the spark plug wire from cylinder 1 by grasping firmly and tugging up.
- Loosen and remove the spark plug using a spark plug socket.
3. Before installing your new spark plug, check the gap of it using a gap tool. If you buy the recommended NGK plugs they should come gaped to around .044 inches (that’s 1.1 mm for the metric folks.) You should not need to actually adjust the gap, but it’s always good to verify it before installing the spark plug in your engine.
4. Install your new spark plug by stuffing it in the spark plug socket and carefully threading it. Do NOT drop the plug down the cylinder, and do NOT tighten with your socket wrench until you ensure it is threading correctly by hand.
5. Torque the new plug to 17 ft-lbs. If you do not have a torque wrench available to you, that is “just snug”. You don’t want to over-tighten the new plug and risk it snapping off inside the cylinder head.
6. Push the spark plug wire firmly back in to the cylinder.
7. Repeat steps for cylinders 2-4.
We hope that this guide has been helpful in walking you through the process of NA Miata spark plug replacement! For more tips and tricks to keep you Miata running smoothly follow us on social media.