2006–2012 Mitsubishi Eclipse
By Ray Delgado ✓ Certified Mechanic · Published Sep 24, 2026 · Updated Oct 14, 2026
Save $313 by doing it yourself! Shop cost: $344
Quick answer: Spark Plug Replacement on a 2006–2012 Mitsubishi Eclipse is rated Moderate and takes about 60–90 minutes. You'll need 5 tools for this job, and parts cost about $31. This guide walks you through the full job step by step, including the mistakes to avoid.
| Part Name | Part Number | Price | Buy |
|---|---|---|---|
| Four OEM-spec long-life platinum spark plugs for the 2006–2012 Eclipse GS 2.4L 4G69 | — | $29.00 | |
| Dielectric grease (small packet) | — | $2.00 | |
| Anti-seize compound (optional, for the plug threads) Optional | — | $3.00 | |
| Throttle-body-safe intake cleaner for the plug wells (optional) Optional | — | $11.00 |
About prices: shown prices are typical retail averages and change frequently; cheaper alternatives may be available. Confirm the current price before buying.
💡 Pro tip: Order all parts at once to save on shipping
Follow these steps carefully
Park the Eclipse level, set the parking brake, and open the hood. Let the 4G69 2.4L cool — the coil packs sit on the valve cover. A cool engine protects the aluminum threads and your hands.
Disconnect the negative battery terminal with a 10 mm wrench and set the cable aside so it can't spring back. On the 4G Eclipse, the battery sits in the driver-side front of the engine bay.
Find the four coil packs on the valve cover. Press the release tab and pull each connector straight off — never yank by the wires. Note the coil order left to right so every coil returns home.
Remove the retaining bolt from each coil pack (typically 10 mm) and lift the coil out of the plug well, setting the coils on a rag in their original order. Inspect each boot for cracks, carbon tracking, or white corrosion.
Before removing the old plugs, blast each plug well with air or a shop vacuum to clear sand and grit — debris in an open cylinder causes immediate scoring. The Eclipse's recessed wells collect road grit.
Remove each plug with a spark-plug socket (rubber insert) on a long extension, tracking each plug's cylinder. Oil on the threads means worn tube seals; heavy white deposits mean a lean condition. Note the gap and wear on the 4G69.
I always keep the old plugs in cylinder order on the bench. If one comes out oily or fouled, that cylinder gets a closer look — plugs are the cheapest diagnostic tool you own.
Gap each new OEM-spec platinum plug with a wire gauge, adjusting only the ground strap — never lever against the center electrode. Anti-seize is optional but popular on aluminum heads. Thread each plug in by hand first, feeling for cross-threading.
Snug each plug down with the ratchet, then wipe the coil packs and press them fully onto the plugs. Reinstall each coil's retaining bolt and reconnect every connector until it clicks; verify each coil is back in its original cylinder.
Reconnect the negative battery terminal and tighten it. Start the engine — the 4G69 should idle smoothly within a minute. Rev and listen for stumbling; if the check-engine light flashes, shut down and recheck the coil connectors.
Test your repair before closing everything up. If something doesn't work right, double-check your steps.
⚠️ Common Mistakes to Avoid
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