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E46 Spark plugs + ignition coils

Why do it

Tools you'll need

• Spark plug socket (5/8" / 16mm) with extension
• Torque wrench
• T30 Torx bit
• 10mm socket
• Small flathead screwdriver
• Compressed air or a straw

Parts to buy

• NGK BKR6EQUP spark plugs (set of 6) The standard plug for 1999–2005 323, 325, 328 and 330 models. You need 6.Fits 1999–2006
• Bremi ignition coil 12131703228 (sold each) For cars built up to 09/2002. Later cars use a newer coil style, so check your car's build date (on the door jamb sticker) before buying.Fits 1999–2002⚠ 2002 cars built after 09/2002 use the newer coil style. Check your build date.

Always double-check fitment for your exact year, trim and transmission before buying. Prices change. ModBuddy doesn't earn money from these links.

Steps

1. Remove the cabin filter housing and engine covers

   • Twist the cabin (micro) filter cover fasteners a quarter turn and lift out the cover and filter.
   • Remove the four T30 Torx screws, unclip the wire cover, move the wires out of their track, and lift out the filter housing.
   • Pry the small caps off the engine cover bolt holes, remove the 10mm bolts and nuts, take off the oil filler cap, and lift off the covers. Put the oil cap back on right away so nothing falls in.
   ✎ Suggest a fix▶ Watch this step (0:12–1:10)

2. Unplug and pull one coil

   • Work on one cylinder at a time so you never mix anything up.
   • Older coils are held by two 10mm bolts. Remove them completely. Newer coils have no bolts.
   • Lift the clip on the connector, unplug it, and pull the coil straight up.
   ✎ Suggest a fix▶ Watch this step (1:10–2:12)

3. Remove the old plug

   • Blow out the hole with compressed air or a straw first, so dirt can't fall into the cylinder.
   • Loosen the plug with a 5/8" (16mm) socket and a hand ratchet, then lift it out with the socket's rubber insert or a magnet.
   ✎ Suggest a fix▶ Watch this step (2:12–3:06)

4. Install the new plug

   • These plugs come pre-gapped. Don't adjust the gap.
   • Thread the new plug in by hand until it seats, then torque it to the spec on the plug box or in your service manual. Never use a power tool to install plugs.

   Tip: If the plug won't turn by hand, stop and back it out. A cross-threaded plug ruins the threads in the aluminum head. The video adds anti-seize. NGK says its plated plugs don't need it, so follow the plug box.

   ✎ Suggest a fix▶ Watch this step (3:06–4:43)

5. Refit the coil and repeat

   • Push the coil (new or old) down onto the plug, plug in the connector and press the tab down until it locks. Refit the bolts snugly if your coil has them.
   • Repeat for the other five cylinders.
   ✎ Suggest a fix▶ Watch this step (4:43–5:10)

6. Reassemble and test

   • Refit the engine covers, the cabin filter housing and its wires, the filter and its cover.
   • Reconnect the battery and start the engine. It should idle smoothly. If the check-engine light was on for a misfire, clear it with a code reader and see if it stays off.
   ✎ Suggest a fix▶ Watch this step (5:10–5:53)

How to know it worked

• Smooth idle with no shaking.
• No flashing check-engine light.
• The misfire code doesn't come back after a few drives.

These are overview steps written to help you plan the job. Always follow the instructions that come with your part and the procedures and torque specs in your factory service manual. Horsepower is an estimate; results vary.