Changing spark plugs is one of the most rewarding DIY car maintenance tasks. It takes 30–90 minutes depending on your vehicle, saves you $100–$300 in labor, and makes a noticeable difference in engine performance. Here's how to do it right.
What You'll Need
- Spark plug socket (5/8" or 13/16" — check your vehicle's spec)
- Socket wrench with extension
- Torque wrench (critical — do not skip this)
- Spark plug gap tool
- Dielectric grease
- Anti-seize compound (for aluminum heads)
- New spark plugs (correct part number for your vehicle)
Step-by-Step Instructions
Step 1: Let the Engine Cool
Never change plugs on a hot engine. Aluminum heads can strip threads when plugs are removed hot. Wait at least 2 hours after last running the engine.
Step 2: Remove One Plug at a Time
Work one plug at a time to avoid mixing up ignition wires or coil packs. Disconnect the wire or coil, blow out any debris from the plug well with compressed air, then unscrew the plug.
Step 3: Inspect the Old Plug
Read the electrode. Light tan color = healthy. Black and sooty = rich mixture or oil burning. White/blistered = lean mixture or overheating. This gives you valuable engine health information.
Step 4: Check the Gap
Even new plugs should be checked against your vehicle's spec. Use a gap tool to verify. Pre-gapped iridium plugs (NGK, Champion) usually come ready to install, but verify anyway.
Step 5: Install and Torque
Thread in by hand first to avoid cross-threading. Then torque to spec with a torque wrench. Overtightening is the #1 DIY mistake — it strips aluminum threads.
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