🔧 Altima - Spark Plug Replacement

On your Altima, the spark plugs sit under the ignition coils on top of the engine. Replacing them restores smooth starting, idle quality, and fuel economy, especially if you’re near the maintenance interval.

Difficulty Level: Intermediate | Estimated Time: 1.0-1.5 hours

---

⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and damaged threads.
• ⚠️ Keep dirt out of the spark plug holes; debris can damage the engine.
• ⚠️ Avoid pulling on wiring; release connector locks before unplugging.
• ⚠️ Battery disconnect is not required, but disconnecting the negative terminal helps prevent accidental shorts.

---

🔧 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")
• 5/8" spark plug socket (rubber insert)
• Torque wrench (3/8" drive, 10-30 ft-lbs range)
• Small flathead screwdriver
• Compressed air nozzle
• Shop vacuum
• Dielectric grease
• Nitrile gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (pre-gapped) - Qty: 4

---

📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Let the engine cool completely (at least 1 hour if it was hot).
• If disconnecting the battery: use a 10mm socket to remove the negative terminal and isolate it so it can’t spring back.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Lift the plastic engine cover straight up to release the rubber grommets.
• If your cover uses fasteners, remove them with a 10mm socket.

Step 2: Unplug and remove the ignition coils

• Locate the four ignition coils on top of the engine.
• Press the connector lock and unplug each coil; use a small flathead screwdriver gently only if the lock tab is stubborn.
• Remove each coil hold-down bolt with a 10mm socket.
• Twist the coil slightly, then pull straight up to remove it.
• Reinstall note: coil bolts are small—Torque to 8 Nm (71 in-lbs).

Step 3: Clean around the spark plug wells

• Blow out each spark plug well using compressed air nozzle.
• If needed, use a shop vacuum to remove loose grit.
• Clean first so dirt can’t fall in.

Step 4: Remove the old spark plugs

• Use a 5/8" spark plug socket (rubber insert) with a 3/8" drive extension and 3/8" drive ratchet to loosen and remove each plug.
• A spark plug socket is a deep socket that grips the plug so it lifts out with the tool.
• If a plug feels extremely tight, stop and work it out slowly (tighten a hair, loosen a hair) to protect the threads.

Step 5: Install the new spark plugs

• Check each new plug for damage. (Most iridium plugs are pre-gapped—don’t pry on the tiny center tip.)
• Start each plug by hand using the 5/8" spark plug socket and extension only (no ratchet at first) to prevent cross-threading.
• Once seated, tighten with a torque wrench: Torque to 18 Nm (13 ft-lbs).
• Hand-starting is the thread-saver.

Step 6: Reinstall ignition coils and connectors

• Apply a very small dab of dielectric grease inside each coil boot (the rubber part that seals to the plug).
• Push each coil straight down until fully seated on the plug.
• Install the coil bolts with a 10mm socket, then finish with a torque wrench: Torque to 8 Nm (71 in-lbs).
• Plug in each coil connector until it clicks.

Step 7: Reinstall the engine cover

• Press the cover back onto its grommets (or install fasteners with a 10mm socket).
• If you disconnected the battery, reconnect the negative terminal using a 10mm socket.

---

✅ After Repair

• Start the engine and let it idle for 30-60 seconds. It should run smooth.
• If the engine shakes or a check engine light appears, shut it off and recheck coil connectors and coil seating.
• Take a short test drive and confirm normal acceleration and no warning lights.

---

💰 DIY vs Shop Cost

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

DIY Cost: $40-$120 (parts only)

You Save: $130-$410 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.

---

🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.