2008 Honda Accord Spark Plug Replacement | Step-By-Step

Replacing spark plugs in a 2008 Accord varies by engine — the 2.4L uses four plugs torqued to 13 ft-lbs, while the 3.5L V6 uses six at 16 ft-lbs.

A 2008 Honda Accord spark plug replacement is a straightforward DIY job that takes about an hour and requires only basic hand tools. The key is identifying your engine type and torquing each plug to the correct spec — getting this wrong can strip the aluminum threads in the cylinder head or crack the valve cover. This guide walks through every step, from gathering parts to torquing the final plug.

What You Need Before Starting

The 2008 Accord came with two engines. Check the Vehicle Emission Control Information label under the hood to confirm yours. The 2.4L four-cylinder uses four NGK Iridium plugs with OEM part number 12290-6A0-A01, a 16mm hex, and a 0.044-inch gap. The 3.5L V6 uses six NGK Laser Iridium plugs. Do not adjust the gap on iridium plugs — if the gap is out of spec, replace the plug entirely.

You’ll need a 16mm spark plug socket with an extension bar, a 10mm socket and ratchet, a torque wrench that reads in ft-lbs, and dielectric grease. If you need new plugs, our best 08 Honda Accord spark plugs roundup compares the top options for both engines so you can pick the right set without guesswork.

How To Replace Spark Plugs On A 2008 Accord

Let the engine cool completely — removing plugs from a hot engine risks stripping threads. Open the hood and release the safety latch. Remove the four 10mm bolts securing the plastic engine cover and set it aside.

Disconnect each ignition coil electrical connector by pressing the clip and wiggling the connector off. Remove the 10mm bolt holding each coil, then lift the coil packs straight up and out — they pull straight off, no twisting needed. Use a 16mm spark plug socket with an extension to turn each old plug counter-clockwise and remove it. Blow compressed air around each plug hole before removing the plug if debris is visible.

Inspect each new plug for defects. Hand-thread it into the hole to prevent cross-threading — this is where most beginners make a costly mistake. Once finger-tight, torque to spec: 13 ft-lbs for the 2.4L or 16 ft-lbs for the V6. Apply a thin layer of dielectric grease inside each coil boot, push the coil down firmly until seated, and reinstall the 10mm mounting bolt (torque to 7.8 ft-lbs — overtightening here cracks the valve cover). Reconnect the electrical connector until it clicks. Repeat for each cylinder, then reinstall the plastic cover and snug the four 10mm bolts.

Torque Specs And Common Mistakes

Torque accuracy is the most critical part of this job. The table below lays out the specs for both engines:

Beyond torque, watch for these common pitfalls: cross-threading (hand-thread every plug), removing plugs from a hot engine, using anti-seize on NGK plugs when not explicitly called for, and overtightening the plastic cover bolts. Honda’s official manual covers the full procedure — Honda’s 2008 Accord owner’s manual includes the factory torque values and maintenance schedule.