How to Replace Ignition Coils on a 2019 Cadillac XT4 (Fix Misfire & Rough Idle)
Step-by-step coil-on-plug replacement with tools, parts list, safety tips, and 10 Nm (89 in-lbs) torque spec for 2019, 2020, 2021, 2022, 2023
How to Replace Ignition Coils on a 2019 Cadillac XT4 (Fix Misfire & Rough Idle)
Step-by-step coil-on-plug replacement with tools, parts list, safety tips, and 10 Nm (89 in-lbs) torque spec for 2019, 2020, 2021, 2022, 2023
đź”§ XT4 - Ignition Coil Replacement
Your XT4 uses “coil-on-plug” ignition coils (one coil per cylinder) mounted on top of the engine. Replacing a bad coil can fix misfires, rough idle, and flashing check-engine light.
Difficulty Level: Beginner | Estimated Time: 0.5-1.5 hours
⚠️ Safety & Precautions
- ⚠️ Let the engine cool fully before working near the turbo/engine cover area.
- ⚠️ Turn ignition OFF and keep the key/fob away from the vehicle so it can’t “wake up” while you’re unplugging coils.
- ⚠️ Disconnect the negative battery cable if you’re worried about accidental shorts.
- ⚠️ Never pull on wiring; always pull on the connector body.
đź”§ Required Tools
You'll need the following tools for this repair:
- 10mm socket
- 3/8" ratchet
- 3/8" extension (3"-6")
- Torque wrench (in-lb or Nm range)
- Plastic trim removal tool
- Small pick tool
- Dielectric grease
- Shop towels
- 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)
- Ignition coil boot (if not included with coil) - Qty: 1 (or Qty: 4)
đź“‹ Before You Begin
- Park on level ground and set the parking brake.
- Open the hood and let the engine cool.
- If disconnecting the battery: use a 10mm socket to remove the negative (-) cable and isolate it so it can’t spring back.
- Decide your approach: replacing 1 coil is OK, but if mileage is high and one failed, many owners replace all 4 to prevent repeat issues.
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Remove the engine cover
- Use your hands to pull the engine cover straight upward to release the rubber grommets.
- If it feels stuck, use a plastic trim removal tool to gently lift at a corner. Pull up—don’t pry hard.
Step 2: Locate the ignition coils
- The coils are the 4 identical modules lined up on top of the engine, each with an electrical connector.
- Pick the cylinder you’re replacing (or work left-to-right so you don’t lose track).
Step 3: Unplug the coil electrical connector
- Use a small pick tool only if needed to gently lift the connector lock/tab.
- Press the release and pull the connector straight off the coil (pull the plastic connector, not the wires).
Step 4: Remove the coil retaining bolt
- Use a 10mm socket, 3/8" ratchet, and 3/8" extension to remove the coil bolt.
- Set the bolt aside on a shop towel so it doesn’t disappear.
Step 5: Remove the ignition coil
- Grip the coil and twist it gently left-right to break the seal, then pull straight upward.
- If the rubber boot stays stuck on the spark plug, use your hand to remove it and transfer it only if your new coil doesn’t include a new boot.
Step 6: Install the new coil
- Put a tiny smear of dielectric grease inside the end of the coil boot (dielectric grease is a non-conductive grease that helps prevent moisture and makes future removal easier).
- Push the coil straight down onto the spark plug until you feel it seat fully.
- Reinstall the retaining bolt by hand first to avoid cross-threading.
- Use a torque wrench to tighten the coil bolt: Torque to 10 Nm (89 in-lbs).
Step 7: Reconnect the coil connector
- Push the connector on until it clicks/locks in place.
- Gently tug the connector to confirm it’s fully seated.
Step 8: Reinstall the engine cover
- Line up the cover with the mounting points and press straight down with your hands until it snaps into the grommets.
Step 9: Reconnect the battery (if disconnected)
- Use a 10mm socket to tighten the negative (-) terminal clamp snugly.
âś… After Repair
- Start the engine and let it idle for 30-60 seconds. It should run smoothly.
- If you had a check-engine light from a misfire, it may take a few drive cycles to turn off, or you can clear codes with a scan tool.
- Take a short test drive and confirm no hesitation under light acceleration.
- If the misfire remains, the next most common causes are the spark plug, injector, or a wiring/connector issue on that cylinder.
đź’° DIY vs Shop Cost
Shop Cost: $250-$650 (parts + labor, depends on replacing 1 coil vs all 4)
DIY Cost: $40-$280 (parts only)
You Save: $210-$370 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.


















