How to Replace Ignition Coils on a 2021 Nissan Altima (Misfire Fix Guide)
Step-by-step DIY instructions with required tools/parts, safety tips, and 8 Nm (71 in-lbs) torque spec for 2019, 2020, 2021, 2022, 2023, 2024
How to Replace Ignition Coils on a 2021 Nissan Altima (Misfire Fix Guide)
Step-by-step DIY instructions with required tools/parts, safety tips, and 8 Nm (71 in-lbs) torque spec for 2019, 2020, 2021, 2022, 2023, 2024
đź”§ Altima - Ignition Coil Replacement
The ignition coils sit on top of your engine and create the high-voltage spark that fires each cylinder. Replacing a bad coil can fix misfires, rough running, and flashing check engine lights.
Difficulty Level: Beginner | Estimated Time: 0.5-1.5 hours
⚠️ Safety & Precautions
- ⚠️ Work on a cool engine to avoid burns.
- ⚠️ Keep the key fob away from the car so it can’t power on unexpectedly.
- ⚠️ Disconnect the negative battery cable if you’re worried about shorting connectors.
- ⚠️ Don’t pull on wiring; release connector locks first.
đź”§ Required Tools
You'll need the following tools for this repair:
- 10mm socket
- 1/4" drive ratchet
- 3" socket extension
- Torque wrench (inch-pound capable)
- Trim clip removal tool
- Small flat-blade screwdriver
- Needle-nose pliers
- Shop rags
- Nitrile gloves
- Safety glasses
🔩 Required Parts
HowToo sells all the parts you need for this repair:
- Ignition coil - Qty: 1
- Dielectric grease - Qty: 1
đź“‹ Before You Begin
- Park on level ground and set the parking brake.
- Let the engine cool fully.
- If disconnecting the battery: use a 10mm socket to remove the negative cable and isolate it so it can’t touch the terminal.
- Take a quick photo before unplugging anything.
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Remove the engine cover (if equipped)
- Gently pull up on the engine cover to release the mounting grommets, or remove any clips using a trim clip removal tool.
- Set the cover aside where it won’t get stepped on.
Step 2: Locate the ignition coil you’re replacing
- The coils are on top of the engine, one per cylinder, each with an electrical connector.
- If you’re chasing a misfire, replace the coil on the cylinder indicated by your scan tool (example: P0302 = cylinder 2).
Step 3: Unplug the ignition coil electrical connector
- Press the connector lock tab and pull the connector straight back.
- If it’s stubborn, use a small flat-blade screwdriver to gently help lift the lock tab while you pull.
- Never yank the wires.
Step 4: Remove the ignition coil hold-down bolt
- Use a 10mm socket, 3" socket extension, and 1/4" drive ratchet to remove the coil’s hold-down bolt.
- Put the bolt somewhere safe so it can’t fall into the engine bay.
Step 5: Remove the ignition coil
- Twist the coil gently left and right to break the seal, then pull it straight up.
- If it’s tight, use needle-nose pliers carefully on the coil body (not the wiring) while pulling upward.
- Use shop rags to keep dirt from falling into the spark plug tube.
Step 6: Install the new ignition coil
- Apply a very small amount of dielectric grease inside the rubber boot of the new coil.
- Push the coil straight down until it fully seats on the spark plug.
Step 7: Reinstall and torque the hold-down bolt
- Start the bolt by hand to avoid cross-threading.
- Use a torque wrench (inch-pound capable) and 10mm socket.
- Torque to 8 Nm (71 in-lbs).
Step 8: Reconnect the electrical connector
- Push the connector on until it clicks/locks.
- Gently tug the connector to confirm it’s latched.
Step 9: Reinstall the engine cover
- Press the cover back onto its grommets, or reinstall clips using a trim clip removal tool.
Step 10: Reconnect the battery (if disconnected)
- Use a 10mm socket to reinstall the negative battery cable.
- Make it snug; do not overtighten.
âś… After Repair
- Start your Altima and let it idle for 1-2 minutes. It should run smoothly.
- If the check engine light was on, clear codes with a scan tool or drive a few cycles if the issue is fixed (some codes clear after multiple good trips).
- Test drive 10-15 minutes and recheck for rough running or a flashing check engine light.
- If the misfire returns, the spark plug for that cylinder may also need replacement.
đź’° DIY vs Shop Cost
Shop Cost: $220-$450 (parts + labor)
DIY Cost: $60-$140 (parts only)
You Save: $160-$310 by doing it yourself!
Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.7-1.2 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.


















