Typically around 105,000 miles for the factory long-life spark plugs on a 2015 Altima (2.5L or 3.5L), with copper plugs needing earlier changes—roughly 30,000–60,000 miles. Always verify the exact interval in your owner’s manual for your engine and plug type.
Engine options and the plug types used in the 2015 Altima
The 2015 Altima was offered with two main engines: a 2.5-liter four-cylinder and a 3.5-liter V6. Both use long-life spark plugs designed to last longer between changes, but the precise part number, gap, and replacement schedule can vary by engine and VIN. If your car has copper plugs or aftermarket replacements, expect shorter intervals.
2.5L four-cylinder (QR25DE)
The 2.5L engine generally uses iridium or platinum long-life spark plugs. The recommended replacement interval is typically around 105,000 miles, though some dealer schedules list 100,000–105,000 miles. Use Nissan-approved plugs and follow the gap and torque specs in your owner's manual.
3.5L V6
The 3.5L V6 also uses long-life plugs with a similar replacement window, around 105,000 miles. Always confirm the exact part number, gap, and torque from the owner's manual or a Nissan service bulletin for your VIN, since there can be small differences by model year or production batch.
Warning signs that spark plugs may need replacement
Replacement may be warranted before reaching the mileage schedule if you notice performance issues or fuel economy drops. Watch for these common indicators:
- Rough idle or engine misfires
- Decreased acceleration or power
- Increased fuel consumption or emissions
- Engine knocking or hesitation under load
- Difficulty starting or a check engine light with misfire codes
A mechanic can diagnose these symptoms and determine whether the plugs, ignition coils, or related components are at fault.
DIY vs professional replacement: planning ahead
Whether you replace the plugs yourself or have a shop handle it depends on your comfort level with modern engines and the tools you have. In the Altima, replacing plugs involves removing coil packs and carefully torquing plugs to specification, so a methodical approach is essential.
- Confirm the correct spark plug part number for your engine and ensure the gap matches the specification.
- Disconnect the battery, remove coil packs to access the plugs, and inspect the ignition coils for wear.
- Carefully remove old plugs with a proper spark plug socket, checking for thread damage in the cylinder head.
- Clean the plug wells, set the correct gap on the new plugs, apply any recommended lubrication or anti-seize per the manual, and thread-by-hand to avoid cross-threading.
- Torque the plugs to the manufacturer’s specification, reinstall the coil packs, and reconnect electrical connectors.
- Start the engine and check for smooth idle and proper operation; reset maintenance reminders if needed.
Professional service can save time, ensure proper torque, and include checks of coils, boots, and gaskets as part of the job.
Maintenance tips for spark plug health
Sticking to the recommended interval and using the correct plug type keeps performance and efficiency high. Regularly inspect ignition coils and boots, and address oil leaks or fouling around the plug wells to extend life between changes.
- Use Nissan-approved or OEM-equivalent spark plugs for your engine.
- Inspect ignition coils and boot seals during a plug change.
- Keep the engine clean and address any signs of fouling or oil intrusion in the plug wells.
Following these practices helps sustain engine performance and avoids surprises at maintenance time.
Summary
The 2015 Nissan Altima typically requires spark plug replacement around 105,000 miles when using long-life iridium or platinum plugs. Copper plugs require earlier changes, usually 30,000–60,000 miles. Always consult the owner’s manual for your exact engine and plug type, and consider professional service if you’re unsure about the procedure or torque specs. Address any performance symptoms promptly to prevent further issues and maintain efficiency.