🔧 Ignition Coils - Replacement

On your Sierra, the ignition coils sit on top of the spark plugs and send high voltage to each cylinder. Replacing a bad coil can fix misfires, rough idle, and loss of power.

Difficulty Level: Beginner | Estimated Time: 1-2 hours

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⚠️ Safety & Precautions

• Ignition systems can deliver a painful shock. Do not touch coil terminals with the engine running.
• Let the engine cool fully before starting. The turbo area and valve cover area can be hot.
• Disconnect the negative battery cable before unplugging coils. This helps prevent accidental shorts.
• Keep dirt out of the spark plug wells. Debris can damage the plugs or cause misfires.
• If your truck has an engine cover or intake duct in the way, remove it carefully first.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4-inch ratchet
• 1/4-inch extension
• Flat-blade trim tool
• Needle-nose pliers
• Torque wrench
• Dielectric grease
• Safety glasses
• Nitrile gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 4
• Ignition coil electrical connector clip - Qty: 1 set

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool down completely.
• Open the hood and remove the key/fob from the vehicle.
• Disconnect the negative battery cable before starting work.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Disconnect battery power

• Use a 10mm socket to loosen the negative battery terminal.
• Move the cable aside so it cannot spring back and touch the post.

Step 2: Remove the engine cover and intake duct if needed

• Pull up on the engine cover by hand if it is installed.
• If the intake duct blocks access, use a flat-blade trim tool and 10mm socket to remove the duct fasteners and clamps.
• Keep all fasteners in a tray.

Step 3: Unplug the ignition coil

• Find the coil on top of each spark plug.
• Use needle-nose pliers if needed to release the connector lock tab.
• Pull the electrical connector straight off the coil.

Step 4: Remove the coil retaining bolt

• Use a 10mm socket and 1/4-inch ratchet to remove the coil bolt.
• Lift the coil straight up and out of the spark plug well.
• Torque on installation: 8 Nm (71 in-lbs).

Step 5: Install the new coil

• Apply a small amount of dielectric grease inside the coil boot.
• Push the new coil straight down onto the spark plug until fully seated.
• Install the retaining bolt by hand first, then tighten with a 10mm socket.
• Torque to 8 Nm (71 in-lbs).

Step 6: Reconnect the electrical connector

• Push the connector onto the coil until it clicks.
• Make sure the lock tab is fully engaged.
• Repeat Steps 3 through 6 for each remaining coil.

Step 7: Reinstall intake parts and engine cover

• Reinstall any intake duct or cover you removed using the 10mm socket and trim tool.
• Make sure all clamps are tight and nothing is left loose in the engine bay.

Step 8: Restore battery power

• Reconnect the negative battery cable using the 10mm socket.
• Tighten the terminal snugly. Do not overtighten.

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✅ After Repair

• Start the engine and let it idle.
• Check for a smooth idle and no warning lights.
• If the check engine light was on, clear codes with a scan tool and road test the truck.
• If a misfire returns, the spark plugs may also need inspection or replacement.

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💰 DIY vs Shop Cost

Shop Cost: $220-$480 (parts + labor)

DIY Cost: $120-$280 (parts only)

You Save: $100-$200 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1-2 hours.

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🎯 Ready to get started?

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