Common signs include engine misfires, rough idle, poor acceleration, decreased fuel economy, and a check engine light with misfire codes (P0300-P0312). Failed coils can also cause hard starting.

While you can replace just the failed coil, it is recommended to replace all coils at once. If one coil has failed, the others are likely nearing the end of their service life too. A complete kit ensures even spark across all cylinders.

Yes. Denso is one of the world's largest OEM auto parts manufacturers, supplying original equipment to Toyota, Honda, Chrysler, GM, Ford, and many other automakers.

It is highly recommended. Worn spark plugs increase the load on ignition coils and can cause premature failure. Replacing both at the same time ensures optimal ignition system performance.

DENSO Iridium spark plugs feature an ultra-fine 0.4mm iridium center electrode that requires less voltage to fire, provides more consistent spark, and lasts up to 100,000 miles. The iridium tip resists wear better than copper or platinum.