A misfire code, rough idle or a check-engine light after a rainstorm usually ends with plugs and coils. The trap is that the same model year can carry two or three engines with different plugs, gaps and coil designs. We match by the engine code, which the VIN carries, and quote full sets so the job is done once.
Coil-on-plug, coil pack or distributor
Most engines from the early 2000s use one coil per cylinder, so a P0301 to P0308 code tells us which coil to look at. Older engines use a coil pack feeding several plugs through wires, and classics use a distributor with a single coil. The three systems share nothing, and the engine code decides which one you have.
Plug type and gap
Iridium plugs last longest and are the factory fit on most engines built after about 2005; platinum and copper plugs suit older engines and cost less. The heat range and gap are engine-specific, and a plug that fits the thread but has the wrong heat range causes exactly the misfire you were trying to fix. Direct-injection and turbocharged engines are the least forgiving.
Replace one coil or the set
On an engine past 100,000 miles, one failed coil means the others are close behind, and the plugs are usually due at the same time. Replacing coils and plugs together avoids repeat labor, especially on V6 and V8 engines where the rear bank is hard to reach. On a newer engine a single coil is a reasonable fix.
Spark Plugs & Ignition Coils by make
- Ford — 5.4 3-valve two-piece plugs need care on removal; EcoBoost engines use their own coils and plugs.
- Chevrolet — 5.3 and 6.2 V8 coils are sold per cylinder; direct-injection engines from 2014 use different plugs.
- GMC — Same engines as Chevrolet; Sierra and Yukon coils match by RPO engine code.
- Nissan — VQ 3.5 V6 rear-bank coils are a common order on Altima, Maxima, Murano and Frontier.
- Hyundai — Sonata and Elantra coil sets; genuine coils are a frequent order on 2.4 engines.
- Cadillac — SRX and CTS 3.6 V6 six-coil sets, sold with iridium plugs.
Read before you buy
Spark Plugs & Ignition Coils FAQ
A scan tool reads the code: P0301 is cylinder 1, P0302 cylinder 2 and so on. Swap the suspect coil with a neighbor; if the code moves, the coil is the fault.
Yes, for coil-pack and distributor engines. Coil-on-plug engines have no wires, only the boot on each coil, which comes with a new coil.
On engines known for coil failures, like the Nissan VQ and some Ford and Hyundai fours, genuine coils last noticeably longer. We quote both so you can choose.