🔧 Altima - Ignition Coil Replacement

You’ll be replacing the ignition coils on your Altima, which sit on top of the engine and provide spark to each cylinder. This will help fix misfires, rough idle, poor fuel economy, and sometimes check-engine lights related to ignition.

Difficulty Level: Beginner | Estimated Time: 1-1.5 hours

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⚠️ Safety & Precautions

• 🔹Always work on a cool engine; hot parts can burn you.
• 🔹Disconnect the negative battery terminal before unplugging ignition components to avoid short circuits.
• 🔹Keep metal tools away from the battery positive terminal to prevent sparks.
• 🔹Do not pull on wires; always use the plastic connectors when disconnecting harness plugs.
• 🔹Work in a well-ventilated area; avoid smoking or open flames near the vehicle.

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🔧 Required Tools

You'll need the following tools for this repair:

• 🔹10mm socket
• 🔹8mm socket
• 🔹1/4" drive ratchet
• 🔹1/4" drive extension (3"-6")
• 🔹Torque wrench (inch-pound or low-range Nm)
• 🔹Flathead screwdriver (small)
• 🔹Needle-nose pliers
• 🔹Plastic trim tool
• 🔹Shop rag
• 🔹Mechanic gloves
• 🔹Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 🔹Ignition coil set (2.5L, all cylinders) - Qty: 4 Replace all four together for best results
• 🔹Dielectric grease (for ignition boots) - Qty: 1 small tube
• 🔹Battery terminal protectant spray - Qty: 1
• 🔹Shop towels - Qty: 1 pack

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📋 Before You Begin

• Park the Altima on level ground, shift to Park, and set the parking brake.
• Turn off the engine and remove the key; let the engine cool for at least 20–30 minutes.
• Open the hood and secure it with the hood prop rod.
• Disconnect the negative battery terminal using a 10mm socket and move the cable aside so it cannot spring back.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove engine cover

• Use a 10mm socket and 1/4" ratchet to remove the bolts (if equipped) holding the plastic engine cover on top of the engine.
• Lift the engine cover straight up; it may also be held by rubber grommets. Wiggle gently to release.
• Set the cover aside in a safe place.

Step 2: Locate the ignition coils

• You will see four ignition coils lined up on top of the engine, each one on top of a spark plug tube, with an electrical connector.
• Identify them now; each coil is a small rectangular unit with a long rubber boot going into the engine.
• Take a quick photo so you remember wiring layout.

Step 3: Disconnect ignition coil electrical connectors

• Put on your mechanic gloves and safety glasses.
• On each ignition coil connector, press the small plastic tab down with your finger or a small flathead screwdriver.
• While the tab is pressed, pull the connector straight back by the plastic housing, not by the wires.
• If a connector is stuck, gently wiggle it side to side. Do not force it; use a plastic trim tool to help pry if needed.

Step 4: Remove ignition coil retaining bolts

• Use an 8mm socket with a 1/4" drive ratchet and extension to remove the single bolt that secures each ignition coil to the valve cover.
• Turn counterclockwise until each bolt is completely loose, then lift them out carefully and keep them in a safe place.
• Keep bolts in order using a small container.

Step 5: Remove the ignition coils

• Grip the top of the first ignition coil and gently twist it left-right while pulling upward to break the seal of the rubber boot.
• Pull the coil straight up out of the spark plug well.
• Repeat for all four coils.
• Inspect each coil boot: if you see oil or heavy carbon tracking (black burn lines), note it; this can signal other issues.

Step 6: Prepare new ignition coils

• Place the new coils on a clean shop rag so they stay free of dirt.
• Apply a very small amount of dielectric grease inside the end of each rubber boot (where it will contact the spark plug). This helps prevent moisture and makes future removal easier.
• Use only a thin smear of grease.

Step 7: Install new ignition coils

• Insert the first new coil into the spark plug well, lining up the boot with the spark plug below.
• Push down firmly until you feel the boot “click” or seat on the plug.
• Align the coil’s mounting tab with the bolt hole in the valve cover.
• Repeat for all four coils, making sure none are crooked.

Step 8: Reinstall ignition coil bolts

• Hand-start each coil bolt by fingers first to avoid cross-threading.
• Use the 8mm socket and ratchet to snug each bolt down lightly in turn.
• Now use a torque wrench with the 8mm socket and tighten each bolt to 8–9 Nm (71–80 in-lbs). Do not overtighten; the threads are in aluminum.

Step 9: Reconnect ignition coil electrical connectors

• Push each electrical connector onto its coil until you hear or feel a positive “click.”
• Lightly tug on each connector to make sure it is locked in place.
• Check that wiring is not twisted or pulled tight; harnesses should sit naturally.

Step 10: Reinstall engine cover

• Place the engine cover back over the top of the engine, aligning it with the mounting points or rubber grommets.
• Press down to seat it into the grommets if present.
• Install any bolts you removed using the 10mm socket and ratchet. Snug them; do not overtighten (typically around 6–8 Nm (53–71 in-lbs)).

Step 11: Reconnect the battery

• Reattach the negative battery cable to the battery post.
• Use the 10mm socket and ratchet to tighten the clamp securely. Do not crush the terminal, just snug.
• Optionally spray a light coat of battery terminal protectant on the terminal to reduce corrosion.

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✅ After Repair

• 🔹Start the engine and let it idle. It should run smoothly without misfire or shaking.
• 🔹If the check engine light was on for an ignition coil code, it may clear on its own after a few drive cycles; or you can clear it with a basic OBD2 scan tool.
• 🔹Test drive the Altima for 10–15 minutes, checking for smooth acceleration and no hesitation.
• 🔹After the drive, open the hood and listen for any unusual noises or smells.

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💰 DIY vs Shop Cost

Shop Cost: $350–$550 (parts + labor) for all four coils

DIY Cost: $160–$260 (parts only, full set of four)

You Save: $190–$290 by doing it yourself!

Shop labor rates 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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