Quick answer: Spark Plug Replacement on a 2017–2020 Hyundai Elantra is rated Advanced and takes about 1-3 hours. You'll need 4 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 2017-2020 Hyundai Elantra; 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
Step-by-Step Instructions
Follow these steps carefully
1
Confirm engine and plug fitment
This guide covers the 2017–2020 Hyundai Elantra with the 2.0-liter Nu four-cylinder, which takes four plugs. The OE plug is the NGK SILZKR7B11 Laser Iridium (NGK stock 9723), pre-gapped to 0.044 in., and Hyundai rates it for roughly a 105,000-mile service interval. Note that the Elantra Eco (1.4L turbo) and Elantra Sport (1.6L turbo) take different plugs — confirm your engine and the part number against your VIN before buying. The 2.0L uses one plug per cylinder with coil-on-plug ignition, and all four coils sit in the open once the engine cover is off.
🔧 Mechanic's note — Tom Becker
The Eco and Sport take different plugs — that's the ordering trap. I confirm the 2.0L Nu against the VIN before buying, because the 1.4T and 1.6T plugs look similar in the catalog and they're not interchangeable.
2
Cool and expose the plugs
Let the engine cool completely — the aluminum head must be cold before plugs come out. Disconnect the battery's negative terminal and pull the engine cover off to expose the four coil packs. Work on one cylinder at a time so coils can't get mixed up.
3
Remove coils and clean wells
Squeeze each coil connector's release tab and unplug it, remove the 10 mm hold-down bolt, and pull the coil straight up with a slight twist. Blow each plug well out with compressed air BEFORE loosening anything — grit falling into an open cylinder causes real damage. Inspect the coil boots for cracks or carbon tracking (white branching marks of voltage leak); at 100,000-plus miles the original boots are often brittle, and a damaged boot causes the misfire you are trying to fix.
🔧 Mechanic's note — Ray Delgado
At 105,000 miles those coil boots are done whether they look it or not — I inspect for the white branching marks of carbon tracking. A brittle boot causes exactly the misfire you're trying to fix, and it's maddening to find afterward.
4
Remove and install plugs
Using a 5/8 in. (16 mm) spark plug socket with an extension, loosen each plug and lift it out. Compare the old plug to the new NGK SILZKR7B11 and confirm the 0.044 in. gap with a wire gauge — the plugs come pre-gapped, so verify rather than adjust, and never lever against the fragile iridium tip. NGK's threads carry a trivalent plating, so install the plugs dry with no anti-seize. Thread each plug in by hand until it seats to avoid cross-threading, then tighten to Hyundai's torque spec.
5
Reconnect and verify
Refit the engine cover and reconnect the battery. Take a short test drive with steady cruising; fresh iridium plugs restore the crisp throttle response these cars gradually lose past 100,000 miles. If a misfire code appears, recheck that cylinder's coil connection first.
All Done!
Test your repair before closing everything up. If something doesn't work right, double-check your steps.
⚠️ Common Mistakes to Avoid
- • Using the wrong plug or assuming a pre-gapped plug needs no verification
- • Blowing debris into an open cylinder or plug well
- • Cross-threading a plug or tightening it without a torque wrench
- • Overusing anti-seize or dielectric grease on the plug threads
- • Mixing coil connectors or ignoring a misfire after reassembly
