How to Replace Ignition Coils on a 2018 Honda Civic (Fix Misfire & Rough Idle)
Step-by-step instructions with required tools, parts, safety tips, and ignition coil torque specs for 2016, 2017, 2018, 2019, 2020, 2021
How to Replace Ignition Coils on a 2018 Honda Civic (Fix Misfire & Rough Idle)
Step-by-step instructions with required tools, parts, safety tips, and ignition coil torque specs for 2016, 2017, 2018, 2019, 2020, 2021
🔧 Civic - Ignition Coil Replacement
Your Civic’s ignition coils sit on top of the engine and send high voltage to the spark plugs. If a coil is weak or failed, you can get misfires, rough idle, poor acceleration, and a flashing check-engine light.
Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours
⚠️ Safety & Precautions
- ⚠️ Work on a cool engine so you don’t burn your hands.
- ⚠️ Turn ignition OFF and keep the key away from the car while unplugging coils.
- ⚠️ If the check-engine light is flashing, avoid driving until fixed (can damage the catalytic converter).
- ⚠️ Battery disconnect is recommended: remove the negative terminal to prevent accidental shorting.
🔧 Required Tools
You'll need the following tools for this repair:
- 10mm socket
- 1/4" drive ratchet
- 6" extension (1/4")
- Torque wrench (in-lb or low-range ft-lb)
- Small flathead screwdriver
- Nitrile gloves
- Safety glasses
🔩 Required Parts
HowToo sells all the parts you need for this repair:
- Ignition coil - Qty: 1 (or Qty: 4 if replacing all)
- Dielectric silicone grease - Qty: 1
📋 Before You Begin
- Park on level ground, set the parking brake, and open the hood.
- Let the engine cool fully.
- Disconnect the battery negative terminal: use a 10mm socket to loosen the clamp and tuck the cable aside so it can’t spring back.
- Tip: Replace coils one at a time to avoid mix-ups.
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Remove the engine cover (if equipped)
- Grip the cover with both hands and pull straight up to pop it off the rubber grommets.
- If any fasteners are present on your cover, remove them with a 10mm socket.
Step 2: Unplug one ignition coil connector
- Locate the coil on top of the engine (one per cylinder).
- Press the connector lock tab and pull the connector straight back.
- If it’s stuck, gently lift the lock with a small flathead screwdriver (don’t pry hard).
Step 3: Remove the coil hold-down bolt
- Use a 10mm socket with a 1/4" ratchet and 6" extension to remove the single bolt holding the coil.
Step 4: Remove the ignition coil
- Twist the coil slightly, then pull straight up to remove it.
- Tip: Don’t yank the wiring harness.
Step 5: Install the new ignition coil
- Put a small smear of dielectric silicone grease inside the rubber boot (dielectric grease is a non-conductive grease that helps prevent moisture and makes future removal easier).
- Push the new coil straight down until it fully seats on the spark plug.
Step 6: Reinstall and torque the hold-down bolt
- Thread the bolt by hand first to avoid cross-threading.
- Use a torque wrench with a 10mm socket and tighten: Torque to 12 N·m (9 ft-lbs).
Step 7: Reconnect the coil electrical connector
- Push the connector on until it clicks/locks.
Step 8: Repeat for the remaining coils (if replacing more than one)
- Repeat Steps 2–7 for each cylinder you’re replacing.
- Tip: If one failed, many owners replace all four.
Step 9: Reconnect battery and reinstall the engine cover
- Reconnect the negative terminal using a 10mm socket.
- Reinstall the engine cover by aligning it and pushing down firmly.
✅ After Repair
- Start the engine and let it idle for 1–2 minutes. It should run smooth.
- If the check-engine light was on, it may take a few drive cycles to clear unless you clear codes with a scan tool.
- If it still misfires, the next common items are spark plugs or a wiring/connector issue.
💰 DIY vs Shop Cost
Shop Cost: $200-$450 (parts + labor)
DIY Cost: $50-$250 (parts only, depending on 1 coil vs all 4)
You Save: $150-$300 by doing it yourself!
Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 hours.
🎯 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.


















