🔧 Niro - Spark Plug Replacement

On your Niro, the spark plugs sit under the ignition coils on top of the engine. Replacing worn plugs helps prevent misfires, rough running, and poor fuel economy, and it’s a straightforward job if you work carefully and keep dirt out of the cylinders.

Difficulty Level: Intermediate | Estimated Time: 1.0-2.0 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and thread damage.
• ⚠️ Hybrid safety: make sure the car is OFF (not READY) and keep the key fob at least 15 ft away so the system can’t wake up.
• ⚠️ Disconnect the 12V battery negative cable before unplugging ignition coils.
• ⚠️ Do not drop anything into the spark plug holes; debris can damage the engine.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8" drive ratchet
• 3/8" drive extension set
• 16mm spark plug socket (rubber insert or magnet)
• Torque wrench (5–40 Nm range)
• Trim clip tool
• Flathead screwdriver
• Compressed air blow gun
• Shop vacuum
• Battery terminal wrench (10mm)
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (iridium type, correct for your Niro) - Qty: 4
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Turn the car OFF and confirm the cluster is OFF (not READY).
• Keep the key fob at least 15 ft away.
• Open the hood and disconnect the 12V battery negative cable using a 10mm battery terminal wrench.
• Wait about 5 minutes before unplugging engine connectors.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Pull upward on the cover to release it, or remove any fasteners using a trim clip tool and flathead screwdriver (some covers use clips).
• Set the cover aside where it won’t get stepped on.

Step 2: Locate the ignition coils

• You’ll see 4 coil packs on top of the engine, one per spark plug.
• One coil = one cylinder.
• Definition: an ignition coil is the “plug wire replacement” that snaps onto the spark plug.

Step 3: Unplug and remove ignition coils

• Press the electrical connector lock tab and unplug each coil connector by hand; use a flathead screwdriver gently only if the tab is stuck.
• Remove each coil hold-down bolt using a 10mm socket, 3/8" ratchet, and extension.
• Twist the coil slightly, then pull straight up to remove it.
• Torque to 7.8–9.8 Nm (69–87 in-lbs) when reinstalling coil bolts.

Step 4: Clean around each spark plug well

• Use a shop vacuum to remove loose dirt around the plug wells.
• Blow out the plug wells using compressed air blow gun.
• Clean first so grit can’t fall in.

Step 5: Remove the old spark plugs

• Insert the 16mm spark plug socket (rubber insert or magnet) with a 3/8" extension and loosen using a 3/8" ratchet.
• Turn counterclockwise until the plug is fully out, then lift it out with the socket.
• If a plug feels extremely tight, stop and re-check alignment to avoid damaging threads.

Step 6: Install the new spark plugs (start by hand)

• Put the new plug into the 16mm spark plug socket and carefully lower it into the hole.
• Thread it in by hand using only the extension (no ratchet at first) to prevent cross-threading.
• Once it seats, tighten with a torque wrench to 14.7–24.5 Nm (11–18 ft-lbs).
• Do not change (gap) iridium plugs unless the plug maker specifically says to; the center tip can be damaged.

Step 7: Reinstall ignition coils

• Apply a small dab of dielectric grease inside each coil boot (the rubber cup) using a gloved finger.
• Push each coil straight down until it fully seats on the plug.
• Install and tighten each coil bolt using a 10mm socket and finish with a torque wrench: Torque to 7.8–9.8 Nm (69–87 in-lbs).
• Reconnect each coil electrical connector until it clicks.

Step 8: Reinstall the engine cover and reconnect the battery

• Reinstall the engine cover (press onto the mounts or reinstall clips using a trim clip tool).
• Reconnect the 12V battery negative cable using a 10mm battery terminal wrench.

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✅ After Repair

• Start the car and confirm it goes to READY normally and idles smoothly.
• If you feel shaking, hear a “puffing” sound, or get a check engine light, shut it off and re-check coil connectors and that every coil is fully seated.
• Test drive 10–15 minutes and recheck for any warning lights.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $60-$180 (parts only)

You Save: $190-$270 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

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🎯 Ready to get started?

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