🔧 Altima - Spark Plug Replacement

Your Altima uses coil-on-plug ignition (each plug has its own “coil pack,” the small module sitting on top of the spark plug). Replacing the plugs restores smooth starting, power, and fuel economy, and helps prevent misfires.

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 damaged threads.
• ⚠️ Keep dirt out of the plug holes—debris can damage the engine.
• ⚠️ Disconnect the negative battery terminal if you’re prone to bumping connectors (recommended for beginners).
• ⚠️ Do not use impact tools on spark plugs or coils.

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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 (3" and 6")
• 3/8" drive swivel adapter
• 14mm spark plug socket (thin-wall, rubber/magnet insert)
• Torque wrench (ft-lb, 10-30 ft-lb range)
• Torque wrench (in-lb, 50-150 in-lb range)
• Flat trim tool
• Compressed air nozzle
• Shop vacuum
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (OEM-style) - Qty: 4
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and open the hood.
• Let the engine cool completely (at least 1 hour after driving).
• If disconnecting the battery: use a 10mm socket to remove the negative terminal and position it so it can’t spring back.
• Lay bolts out in order as you remove them.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Remove the plastic engine cover fasteners using a 10mm socket or a flat trim tool (depends on what your cover uses).
• Lift the cover up and set it aside.

Step 2: Unplug and remove ignition coils

• Each cylinder has an ignition coil on top of the plug. (A “coil pack” makes the spark for that one plug.)
• Press the electrical connector tab and unplug each coil connector. Use a flat trim tool only if needed—don’t break the tab.
• Remove the coil retaining bolt using a 10mm socket and 3/8" drive ratchet.
• Pull the coil straight upward to remove it. If it’s stuck, gently twist while pulling.
• Torque on install: coil bolts Torque to 8.5 Nm (75 in-lbs)

Step 3: Clean the spark plug wells

• Blow out each plug well using a compressed air nozzle.
• If you see loose sand/grit, use a shop vacuum to remove it.
• Cleaning first prevents debris falling into the cylinder.

Step 4: Remove the old spark plugs

• Install a 14mm spark plug socket (thin-wall, rubber/magnet insert) on a 3/8" drive extension set (3" and 6") (add the 3/8" drive swivel adapter if you need angle).
• Turn counterclockwise to loosen, then remove the plug fully.
• Repeat for all 4 cylinders.

Step 5: Install the new spark plugs

• Confirm you have 4 matching iridium plugs. Most iridium plugs come pre-gapped—avoid bending the tiny tip.
• Place the new plug into the 14mm spark plug socket (thin-wall, rubber/magnet insert).
• Thread the plug in by hand using only the 3/8" drive extension set (3" and 6") (no ratchet at first). It should spin in smoothly.
• Tighten with a torque wrench (ft-lb, 10-30 ft-lb range): Torque to 20 Nm (15 ft-lbs)
• Do not add anti-seize to Nissan-style plated spark plug threads unless the plug maker specifically says to.

Step 6: Reinstall ignition coils

• Put a tiny amount of dielectric grease inside each coil boot. (Dielectric grease is a non-conductive grease that helps prevent moisture and makes future removal easier.)
• Push the coil straight down until it fully seats on the plug.
• Install the coil bolt with a 10mm socket, then tighten with a torque wrench (in-lb, 50-150 in-lb range): Torque to 8.5 Nm (75 in-lbs)
• Reconnect each electrical connector until it clicks.

Step 7: Reinstall the engine cover

• Reinstall the cover and fasteners using a 10mm socket or flat trim tool (whichever your cover uses).

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✅ After Repair

• Reconnect the battery negative terminal (if removed) using a 10mm socket.
• Start the engine and let it idle for 30-60 seconds. It should run smooth with no shaking.
• If the check engine light is on or it runs rough, re-check that every coil connector is fully clicked in.
• Road test 5-10 minutes and recheck for any abnormal smell or warning lights.

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💰 DIY vs Shop Cost

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

DIY Cost: $60-$140 (parts only)

You Save: $190-$310 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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