2020–2024 Cadillac CT5
By Ray Delgado ✓ Certified Mechanic · Published Sep 21, 2026 · Updated Oct 22, 2026
Save $335 by doing it yourself! Shop cost: $450
Quick answer: Spark Plug Replacement on a 2020–2024 Cadillac CT5 is rated Advanced and takes about 1–1.5 hours (2.0T/3.0TT); 2 hours (Blackwing V8). You'll need 5 tools for this job, and parts cost about $115. This guide walks you through the full job step by step, including the mistakes to avoid.
| Part Name | Part Number | Price | Buy |
|---|---|---|---|
| Correct spark plug set for the gasoline/ICE engine in 2020-2024 Cadillac CT5; verify engine, heat range, gap, and VIN fitment | — | $115.00 | |
| Coil-boot seals or ignition coils only if inspection finds damage Optional | — | $35.00 |
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
The CT5 spans three engines with three different plug counts, so confirm yours first: the base 2.0-liter turbo four-cylinder (LSY) takes four plugs, the CT5-V's 3.0-liter twin-turbo V6 (LGY) takes six, and the CT5-V Blackwing's supercharged 6.2-liter V8 (LT4) takes eight.
Lift it evenly from both sides so no stud snaps, and set it aside. On the Blackwing V8, also check whether the strut tower brace crosses over the rear coils; if it does, unbolt it and lift it out for the access it buys you.
I tighten plastic fasteners by hand and stop at snug. Every stripped plastic thread I've repaired started with 'just a little more.'
Press the tab, slide the connector off, remove the bolt, and pull the coil straight up out of its well. On the Blackwing's V8 the plugs angle into deep wells beside the exhaust manifolds, so work deliberately and keep each coil with its cylinder.
Blow or brush all debris away from the open wells, then remove each plug with a 5/8-inch spark plug socket and an extension — a longer extension helps on the V8's deep, angled wells.
Never invent a gap value — check the correct gap on the under-hood emissions sticker or in the owner's manual and verify each new plug with a wire-type gauge, adjusting only the ground electrode. Compare each new plug against the old one for matching thread length and reach before installing. Start every plug by hand for several full turns so you know the threads are engaged — cross-threading an aluminum head is the one mistake that turns this into a shop bill.
These are aluminum heads on all three engines, so overtightening strips the threads with very little warning — favor the lighter side, especially on the V8's angled rear plugs.
Press each coil firmly back onto its plug, reinstall the retaining bolts, and reconnect every connector until the locking tab clicks. Start the engine and confirm a smooth idle with no warning lights, then take a short drive to verify clean acceleration.
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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