BMW Spark Plug Replacement Guide

Spark plugs are one of the most overlooked maintenance items on BMWs. Here's everything you need to know.

Replacement Intervals

Engine	Interval	Plug Type
N52	60,000 km	NGK PLZKBR7B8DG or Bosch ZR5TPP33
N54	15,000-20,000 km	NGK 97506 (1-step colder)
N55	40,000-60,000 km	NGK 94201 or Bosch ZR5TPP33S
B58	40,000-60,000 km	NGK 97506
S55	15,000-20,000 km	NGK 97506
N20	40,000-60,000 km	NGK PLZKBR7B8DG
B48	40,000-60,000 km	NGK 97506
M54	60,000-80,000 km	NGK BKR6EQUP or Bosch FR7LPP33+

Note: Turbocharged engines (N54, S55) need more frequent changes because higher combustion pressures and temperatures wear plugs faster.

Why Spark Plugs Matter

Worn spark plugs cause:

• Misfires (P0301-P0306 codes)
• Rough idle
• Reduced power
• Poor fuel economy
• Failed emissions
• Catalytic converter damage (from unburned fuel)

How to Replace (Inline-6 Example)

1. Remove the engine cover (pull up, it's clip-mounted)
2. Disconnect the coil pack connectors (squeeze the tab and pull)
3. Remove the coil pack bolts (8mm or 10mm)
4. Pull out the coil packs
5. Use a spark plug socket (14mm thin-wall with rubber insert) with an extension
6. Remove old plugs — they may be tight if they've been in a long time
7. Gap new plugs if needed (most come pre-gapped)
8. Install new plugs — hand-tighten first, then torque to 22-25 Nm
9. Reinstall coil packs and connectors
10. Reinstall engine cover

Time: 30-60 minutes
Cost: €30-80 for plugs (vs €200-400 at a shop)

Common Mistakes

• Cross-threading — always start by hand. If it doesn't thread easily, stop and realign.
• Overtightening — aluminum heads strip easily. Use a torque wrench.
• Wrong plug — always use the specified plug. Wrong heat range can cause detonation or fouling.
• Ignoring coil packs — if a coil pack is weak, a new plug won't fix the misfire. Replace coils with plugs if they're original and over 80,000 km.

Should I Upgrade to Iridium/Platinum?

BMW already specifies iridium or platinum plugs for most engines. Don't "upgrade" to a different type — use what BMW specifies. The engineers chose that plug for a reason.