For a 2015 Honda Accord, spark plugs should typically be replaced around 105,000 miles (about 168,000 km) under normal driving. This interval applies to both the 2.4L inline-4 and the 3.5L V6 engines with long-life plugs. If you regularly drive under severe conditions or notice performance issues, you may need to change them earlier.
Official maintenance interval
Honda’s schedule for the 2015 Accord lists spark plug replacement at 105,000 miles or 7 years, whichever comes first, with the same target for both engine variants. The car uses long-life iridium/platinum-type plugs designed to stretch the interval beyond older copper plugs.
Sticking to the factory interval helps preserve smooth starts, fuel economy, and overall engine performance. If your driving is considered severe—such as frequent short trips, heavy traffic in hot or dusty environments, or towing—consider planning for an earlier inspection or replacement.
Summary of the official interval by engine:
- 2.4L inline-4 engine: replace at 105,000 miles (168,000 km) or 7 years, whichever comes first.
- 3.5L V6 engine: replace at 105,000 miles (168,000 km) or 7 years, whichever comes first.
Following this schedule is intended to sustain optimal performance and efficiency. Always verify with your owner's manual or a Honda service professional for any model-specific notes or campaigns.
Signs you may need an earlier change
Even if you’re near the recommended mileage, certain symptoms can indicate worn plugs or related ignition issues. Look out for:
- Engine misfires or a rough idle
- Reduced fuel economy or noticeable power loss
- Long or hard starting, or cranking without firing
- Engine knocking or pinging under load
- Check Engine Light with misfire-related codes (such as P0300-series)
- Deterioration in acceleration or overall drivability
If you notice these signs, have your spark plugs inspected promptly. A technician may recommend replacement and also check ignition coils and wires, especially on higher-mileage vehicles.
What to expect during replacement
Replacing spark plugs on a 2015 Accord is a routine service that a qualified technician can perform in about an hour per engine bank. The process generally involves accessing the spark plugs by removing the coil packs, inspecting the ignition system, and installing new plugs to the manufacturer’s torque specification. Pros often avoid anti-seize on modern iridium/platinum plugs, and plugs are typically pre-gapped and designed to last the stated interval. Labor and parts costs vary by region and trim level.
Steps commonly involved include:
- Ensure the engine is cool before starting any work.
- Disconnect the battery and remove the ignition coil packs to access the plugs.
- Carefully remove old plugs and inspect threads and cylinders.
- Install new plugs, torque to the manufacturer spec (around typical 13 ft-lbs, but verify exact value in the manual).
- Reinstall coil packs, reconnect wiring, and perform a system check after starting the engine.
Note: Always rely on the official maintenance guidelines or a Honda-certified technician for exact torque specs and procedures for your specific trim and engine.
Summary
The standard spark plug replacement interval for the 2015 Honda Accord is about 105,000 miles (7 years), whichever comes first, for both the 2.4L and 3.5L engines using long-life plugs. Consider earlier replacement under severe driving conditions or if you experience symptoms such as misfires, reduced fuel economy, or hard starting. Regular maintenance helps preserve performance and efficiency, and professional service is recommended to ensure proper installation and torque.