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