🔧 GS350 - Ignition Coil Replacement

Your GS350 uses one ignition coil per cylinder (6 total). Replacing a bad coil can fix misfires, rough idle, flashing check-engine light, and loss of power.

Difficulty Level: Intermediate | Estimated Time: 1.0-2.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and damaged connectors.
• ⚠️ If the check-engine light is flashing, avoid driving until repaired (can damage the catalytic converters).
• ⚠️ Disconnect the negative battery cable to reduce the chance of shorting or setting extra faults.
• ⚠️ Pull on connector housings, not wires (prevents broken wiring).

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4" drive ratchet
• 3" extension (1/4" drive)
• 6" extension (1/4" drive)
• Universal swivel joint (1/4" drive)
• Torque wrench (inch-pound)
• Trim clip removal tool
• Small flathead screwdriver
• Needle-nose pliers
• Shop light
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coils - Qty: 6 (replace only failed coils if desired)
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool completely.
• Use a 10mm socket to disconnect the negative battery cable and isolate it so it can’t spring back.
• Take a quick photo of each connector layout.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Grip the cover and pull upward to release the grommets (rubber push-in mounts).
• If any plastic clips or small covers block access, remove them with a trim clip removal tool.

Step 2: Unplug the ignition coil electrical connector

• At the coil, press the connector release tab and pull the connector straight off.
• If it’s stuck, gently help the tab with a small flathead screwdriver (don’t pry hard).
• Wiggle the connector—don’t yank the wires.

Step 3: Remove the ignition coil hold-down bolt

• Use a 10mm socket with a 1/4" drive ratchet and the 3" or 6" extension to remove the bolt.
• For tight coils, add a universal swivel joint (1/4" drive) to angle the socket.

Step 4: Remove the old coil

• Twist the coil slightly to break the seal, then pull it straight up and out.
• If it’s very tight, rotate more and pull upward evenly (avoid side-loading the coil boot).

Step 5: Prep and install the new coil

• Apply a small smear of dielectric grease inside the coil boot (the rubber tube that seals to the spark plug).
• Push the new coil straight down until it fully seats on the spark plug.
• Reinstall the hold-down bolt by hand first (prevents cross-threading).
• Tighten with a torque wrench: Torque to 10 Nm (89 in-lbs).

Step 6: Reconnect the coil connector

• Push the connector on until it clicks.
• Do a gentle tug check to confirm it’s locked.

Step 7: Repeat for remaining coils

• Repeat Steps 2–6 for each coil you’re replacing.
• If access is tight on the rear bank, use the shop light, 6" extension, and swivel joint to keep the socket straight on the bolt.

Step 8: Reinstall the engine cover and reconnect battery

• Press the engine cover back onto its mounting grommets.
• Reconnect the negative battery cable using a 10mm socket (snug, do not over-tighten).

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✅ After Repair

• Start the engine and let it idle for 1–2 minutes. It should be smooth (no shaking).
• Verify the check-engine light is off. If it stays on, it may need clearing after the repair.
• Take a short test drive and recheck for warning lights or new symptoms.
• If you still have a misfire, the next common cause is spark plugs or a fuel/air issue.

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💰 DIY vs Shop Cost

Shop Cost: $300-$750 (parts + labor)

DIY Cost: $180-$600 (parts only, depending on how many coils)

You Save: $120-$300+ by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-2.0 hours.

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🎯 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.