🔧 Altima - Ignition Coil Replacement

Replacing the ignition coils on your Altima can fix engine misfires, rough idle, hesitation, poor fuel economy, and a flashing check engine light. The V6 has six coils total; the front three are easy to reach, while the rear three require removing the upper intake manifold.

Difficulty Level: Intermediate | Estimated Time: 2-3.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work only on a completely cool engine to avoid burns from hot aluminum parts and coolant hoses.
• 🔋 Disconnect the negative battery cable before unplugging ignition coils or engine sensors.
• 🧤 Wear safety glasses and nitrile gloves to protect your eyes and hands.
• 🚫 Do not allow bolts, dirt, rags, or tools to fall into the open intake ports.
• 📌 Cover open intake ports with clean shop towels immediately after removing the upper intake manifold.
• ⚠️ If the check engine light flashes after repair, stop driving and recheck the coil connectors and intake hoses.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 14mm socket
• 1/4-inch ratchet
• 3/8-inch ratchet
• 3-inch socket extension
• 6-inch socket extension
• 1/4-inch torque wrench
• 3/8-inch torque wrench
• Flat-blade screwdriver
• Needle-nose pliers
• Trim clip removal tool
• Magnetic pickup tool
• Flashlight
• Painter’s tape
• Marker
• Clean shop towels
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coils - Qty: 6
• Upper intake manifold gasket set - Qty: 1
• Throttle body gasket - Qty: 1
• Spark plugs - Qty: 6

Best practice: replace all six coils together.

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📋 Before You Begin

• 🚗 Park your Altima on level ground, shift to Park, and set the parking brake.
• ❄️ Let the engine cool for at least 1 hour.
• 🔋 Use a 10mm socket to disconnect the negative battery cable.
• 🏷️ Use painter’s tape and a marker to label hoses and connectors before unplugging them.
• 📌 A torque wrench tightens bolts to an exact tightness so parts are not cracked or stripped.
• 📌 A trim clip removal tool is a small pry tool that releases plastic wire clips without breaking them.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Engine Cover

• Use both hands to pull the plastic engine cover straight upward from the rubber mounting grommets.
• Place the cover aside where it will not be stepped on.
• Pull evenly, not sideways.

Step 2: Disconnect the Negative Battery Cable

• Use a 10mm socket and 3/8-inch ratchet to loosen the negative battery terminal nut.
• Lift the negative cable off the battery post.
• Move the cable aside so it cannot touch the post while you work.

Step 3: Remove the Air Intake Duct

• Use a flat-blade screwdriver to loosen the hose clamp at the throttle body.
• Use a flat-blade screwdriver to loosen the hose clamp at the air filter housing.
• Use needle-nose pliers to release any small hose clamps attached to the intake duct.
• Lift the intake duct out of the engine bay.

Step 4: Disconnect Intake Sensors and Hoses

• Use your fingers to press the mass air flow sensor connector tab, then unplug the connector.
• Use painter’s tape and a marker to label every hose and connector before removing it.
• Use needle-nose pliers to squeeze spring clamps and slide them back from hose ends.
• Use a trim clip removal tool to release wiring harness clips from brackets.

Step 5: Remove the Throttle Body

• Use a 10mm socket, 3-inch extension, and 3/8-inch ratchet to remove the throttle body bolts.
• Move the throttle body aside without pulling hard on the wiring or coolant hoses.
• If coolant hoses must come off, use needle-nose pliers to release the hose clamps and catch small drips with clean shop towels.
• Remove and discard the old throttle body gasket.
• During installation, use a 1/4-inch torque wrench to tighten the throttle body bolts to Torque to 8.8 Nm (78 in-lbs).

Step 6: Disconnect Upper Intake Manifold Attachments

• Use painter’s tape and a marker to label all vacuum hoses, electrical connectors, and brackets on the upper intake manifold.
• Use needle-nose pliers to move spring clamps away from hose ends.
• Use a flat-blade screwdriver gently at the hose edge if a hose is stuck.
• Use a trim clip removal tool to release wiring retainers from the manifold.

Step 7: Remove the Upper Intake Manifold

• Use a 12mm socket, 6-inch extension, and 3/8-inch ratchet to remove the upper intake manifold bolts.
• Use a 10mm socket and 3/8-inch ratchet to remove any small support bracket bolts.
• Lift the upper intake manifold straight up and away from the engine.
• Immediately place clean shop towels into the open intake ports.
• Remove and discard the old upper intake manifold gaskets.
• During installation, use a 3/8-inch torque wrench to tighten the upper intake manifold bolts evenly to Torque to 19.6 Nm (14 ft-lbs).

Step 8: Locate the Ignition Coils

• Use a flashlight to locate all six ignition coils on top of the engine.
• Each ignition coil is a black electrical part held by one 10mm bolt and one connector.
• An ignition coil sends high-voltage spark to the spark plug so the cylinder can fire.

Step 9: Unplug the Ignition Coil Connectors

• Use your finger to press the lock tab on each ignition coil connector.
• Pull the connector body straight off the coil.
• If a tab is stubborn, use a flat-blade screwdriver gently on the lock tab only.
• Do not pull on the wires.

Step 10: Remove the Old Ignition Coils

• Use a 10mm socket, 3-inch extension, and 1/4-inch ratchet to remove each ignition coil retaining bolt.
• Twist each coil slightly by hand to loosen the rubber boot.
• Pull each coil straight upward out of the spark plug tube.
• Use a magnetic pickup tool if a bolt drops into a tight area.

Step 11: Install the New Ignition Coils

• Push each new ignition coil straight down into the spark plug tube until it seats fully.
• Use a 10mm socket and 1/4-inch ratchet to start each retaining bolt by hand.
• Use a 1/4-inch torque wrench to tighten each ignition coil bolt to Torque to 5.4 Nm (48 in-lbs).
• Reconnect each ignition coil connector until it clicks.
• The click means it is locked.

Step 12: Install New Intake Gaskets

• Use clean shop towels to wipe the intake gasket sealing surfaces.
• Remove all shop towels from the intake ports before installing the manifold.
• Place the new upper intake manifold gaskets into their grooves.
• Use a flashlight to confirm no bolts, rags, or debris are near the intake openings.

Step 13: Reinstall the Upper Intake Manifold

• Lower the upper intake manifold straight into place.
• Use a 12mm socket and 6-inch extension to start every manifold bolt by hand.
• Use a 3/8-inch torque wrench to tighten the manifold bolts evenly in stages to Torque to 19.6 Nm (14 ft-lbs).
• Use a 10mm socket and 3/8-inch ratchet to reinstall any support brackets.

Step 14: Reconnect Hoses, Wiring, and Brackets

• Use your painter’s tape labels to reconnect every hose and connector to its original location.
• Use needle-nose pliers to slide spring clamps back over hose ends.
• Press electrical connectors by hand until they click.
• Use the trim clip removal tool to guide wiring clips back into their holders if needed.

Step 15: Reinstall the Throttle Body

• Install the new throttle body gasket.
• Set the throttle body back onto the intake manifold.
• Use a 10mm socket and 3-inch extension to start all throttle body bolts by hand.
• Use a 1/4-inch torque wrench to tighten the throttle body bolts evenly to Torque to 8.8 Nm (78 in-lbs).
• Reconnect any throttle body hoses and connectors.

Step 16: Reinstall the Air Intake Duct

• Fit the air intake duct onto the throttle body and air filter housing.
• Use a flat-blade screwdriver to tighten both intake duct clamps snugly.
• Use needle-nose pliers to reinstall any small hose clamps.
• Reconnect the mass air flow sensor connector until it clicks.

Step 17: Reconnect the Battery

• Place the negative battery cable back onto the battery post.
• Use a 10mm socket and 3/8-inch ratchet to tighten the terminal nut snugly.
• Do not overtighten it because the battery terminal can crack.

Step 18: Reinstall the Engine Cover

• Line up the plastic engine cover with the rubber mounting grommets.
• Push the cover down by hand until it seats securely.

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✅ After Repair

• ✅ Start the engine and let it idle for 2-3 minutes.
• 👂 Listen for hissing noises, which can mean a vacuum hose or intake gasket leak.
• 🔍 Check that all ignition coil connectors, sensor connectors, and hoses are fully seated.
• 🚗 Test drive your Altima gently for 10-15 minutes.
• 🧠 If idle is high or unstable after throttle body removal, an idle air volume relearn may be needed with a compatible scan tool.
• ⚠️ If the check engine light flashes, stop driving and recheck coil connectors and intake hoses.

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💰 DIY vs Shop Cost

Shop Cost: $650-$1,100 (parts + labor)

DIY Cost: $180-$450 (parts only)

You Save: $470-$650 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-3 hours.

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