Quick answer: Spark Plug Replacement on a 2015–2023 Ford Mustang is rated Moderate and takes about 45-90 minutes. You'll need 4 tools for this job, and parts cost about $41. This guide walks you through the full job step by step, including the mistakes to avoid.
Parts You Need
The options below are alternatives for the same part — you only need to buy one. Pick the one that matches your year and engine.
| Part Name |
Part Number |
Price |
Buy |
| Spark plugs (correct heat range) |
— |
$35.00 |
|
| Dielectric grease |
— |
$6.00 |
|
| Spark Plugs (Motorcraft CYFS-12F-1X / SP-548, 5.0L V8, set of 8) Optional |
CYFS-12F-1X |
— |
|
| Spark Plugs (Motorcraft SP-594, 2.3L EcoBoost, set of 4) Optional |
SP-594 |
— |
|
About prices: shown prices are typical retail averages and change frequently; cheaper alternatives may be available. Confirm the current price before buying.
💡 Pro tip: Compare the options above and order the one that matches your vehicle — you only need one.
Step-by-Step Instructions
Follow these steps carefully
1
Confirm engine and plug fitment
Confirm the engine in your 2015-2023 Mustang. The 5.0L Coyote V8 takes the Motorcraft CYFS-12F-1X (SP-548) platinum plug — buy 8, pre-gapped; verify the spec in your owner's manual rather than adjusting. The 2.3L EcoBoost four takes Motorcraft SP-594, gapped at 0.030 in — buy 4, pre-gapped finewire, do not touch the gap. Scan for P0300-series misfires first.
🔧 Mechanic's note — Ray Delgado
I never skip this part: The 2.3L EcoBoost four takes Motorcraft SP-594, gapped at 0.030 in — buy 4, pre-gapped finewire, do not touch the gap.
2
Cool and expose the plugs
Let the engine cool completely and disconnect the negative battery cable. Remove the engine cover; on the Coyote the strut tower brace should come off for coil access. Swivel sockets help here.
3
Remove coils and clean wells
Unplug each coil connector, remove the hold-down bolt, and lift the coil straight up. Blow or brush every plug well clean before loosening a plug — the deep Coyote wells collect grit against the cowl.
4
Remove and install plugs
Start each new Motorcraft plug by hand and tighten to the manufacturer's spec in your owner's manual — never an impact gun. On the EcoBoost, verify the 0.030 in gap but do not pry on the finewire tips.
🔧 Mechanic's note — Ray Delgado
I tell every DIYer who'll listen: Start each new Motorcraft plug by hand and tighten to the manufacturer's spec in your owner's manual — never an impact gun.
5
Reconnect and verify
Reinstall the coils, connectors, strut tower brace, and cover; reconnect the battery. The Coyote should idle with its even V8 lope and the EcoBoost pull cleanly under boost; any stumble points to a coil connector that didn't seat, not the new plugs.
All Done!
Test your repair before closing everything up. If something doesn't work right, double-check your steps.
⚠️ Common Mistakes to Avoid
- • Cross-threading the plug in the head
- • Skipping the torque wrench / overtightening
- • Wrong gap or heat range for the engine
- • Mixing up ignition coil connectors by cylinder
