🔧 K900 - Ignition Coil Replacement

Ignition coils sit on top of the spark plugs and create the high voltage needed for ignition. On your K900’s 3.8L V6, the front bank is easy to reach, but the rear bank coils are typically under the intake manifold, so the job can range from simple to fairly involved.

Assumption: Rear-bank access requires intake manifold removal (common on this 3.8L layout).

Difficulty Level: Advanced | Estimated Time: 2.5-5.0 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cold engine; the intake and heads get very hot.
• ⚠️ Disconnect the negative battery terminal to prevent accidental shorting.
• ⚠️ Keep dirt out of intake ports; cover openings with clean shop towels.
• ⚠️ Don’t pull on wiring—release connectors by the lock tab first.
• ⚠️ If you smell fuel while disconnecting lines, stop and ventilate the area.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 12mm socket
• 14mm socket
• 3/8" drive ratchet
• 3/8" drive torque wrench (5–30 Nm range)
• 6" extension (3/8")
• 10" extension (3/8")
• Universal swivel joint (3/8")
• Flat trim tool
• Needle-nose pliers
• Pick tool
• Magnetic pickup tool
• Shop towels
• Masking tape
• Paint marker

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 6
• Intake manifold gasket set - Qty: 1
• Throttle body gasket - Qty: 1
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Disconnect the battery: use a 10mm socket to remove the negative terminal and tuck it aside.
• Label hoses/connectors with masking tape as you unplug them. This prevents mix-ups during reassembly.
• Have shop towels ready to cover the intake ports once the manifold is off.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Pull up firmly on the engine cover to release the rubber grommets. Use a flat trim tool if it’s stuck.

Step 2: Remove the air intake ducting (for working room)

• Use a 10mm socket to loosen the intake hose clamps and remove any air duct brackets.
• Lift the ducting out and set it aside.

Step 3: Replace the front-bank coils (closest to the radiator)

• On each coil, press the connector lock tab and unplug it. Use a pick tool gently if the tab is stubborn.
• Remove the coil hold-down bolt using a 10mm socket and 3/8" ratchet.
• Twist the coil slightly and pull straight up to remove it. Don’t pry on the plastic.
• Apply a light smear of dielectric grease inside the new coil boot (this helps prevent moisture and future sticking).
• Install the new coil straight down until it fully seats on the plug.
• Reinstall the bolt and Torque to 10 Nm (7 ft-lbs) using a torque wrench.
• Reconnect the electrical connector until it clicks.

Step 4: Prepare to remove the intake manifold (for rear-bank coil access)

• Unplug the throttle body connector and any nearby sensors using your fingers or a pick tool (release tabs first).
• Remove vacuum/EVAP hoses carefully using needle-nose pliers to slide spring clamps back.
• Use masking tape to label each hose/connector as you remove it.

Step 5: Remove the throttle body (if required for manifold removal)

• Use a 10mm socket to remove the throttle body bolts.
• Separate the throttle body and remove the old gasket.
• Set the throttle body aside (avoid stressing any coolant hoses if equipped).

Step 6: Remove the upper intake manifold

• Remove manifold bolts using a 12mm socket, ratchet, and extensions as needed.
• Use a magnetic pickup tool to prevent dropping bolts into the engine bay.
• Lift the manifold off carefully.
• Immediately stuff clean shop towels into the intake ports to keep hardware/dirt out.

Step 7: Replace the rear-bank coils (closest to the firewall)

• Unplug each coil connector (release the tab first).
• Remove each coil bolt with a 10mm socket.
• Twist and pull the coil straight up to remove.
• Add a thin coat of dielectric grease inside each new boot.
• Install the new coils, reinstall bolts, and Torque to 10 Nm (7 ft-lbs).
• Reconnect the connectors until they click.

Step 8: Reinstall the intake manifold with new gaskets

• Remove the shop towels from the intake ports.
• Install new intake manifold gaskets (make sure they sit flat and don’t pinch).
• Set the manifold in place and hand-start all bolts.
• Tighten bolts evenly in a crisscross pattern using a 12mm socket.
• Torque to 20 Nm (15 ft-lbs) using a torque wrench.

Step 9: Reinstall the throttle body and intake ducting

• Install a new throttle body gasket.
• Reinstall throttle body bolts with a 10mm socket and Torque to 10 Nm (7 ft-lbs).
• Reconnect all hoses and electrical connectors (match your labels).
• Reinstall the air intake ducting and tighten clamps using a 10mm socket.

Step 10: Reconnect battery and reinstall engine cover

• Reconnect the negative terminal using a 10mm socket.
• Press the engine cover back onto its mounting grommets.

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✅ After Repair

• Start the engine and let it idle for 1–2 minutes. It should run smooth with no shaking.
• Listen for intake vacuum leaks (a hissing sound). If present, recheck manifold hoses and gasket seating.
• If the check engine light stays on, the stored misfire code may need clearing with a scan tool after the repair.
• Test drive gently for 10 minutes and recheck for any fuel smell or abnormal idle.

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💰 DIY vs Shop Cost

Shop Cost: $500-$1,200 (parts + labor)

DIY Cost: $180-$600 (parts only)

You Save: $320-$600 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.5-5.0 hours.

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🎯 Ready to get started?

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