E46 Spark Plug DIY

I changed my spark plugs last weekend and I thought I would document it for the benefit of other less mechanically experienced board members like myself but who know just the basics.

My car is an E46 2001 325i. Spark plugs used : BMW OEM (NGK BKR6EQUP).
Tools needed: T30 Torx bit screwdriver, flat head screwdriver, ratchet, 10mm socket, 6" extension bar, 5/8" spark plug socket.

Step 1
Open the cabin microfilter cover and remove the microfilter. Unscrew the 4 Torx screws (T30) highlighted, in the microfilter housing. Carefully snap off the 4 clips holding the 2 cables in the front of the housing. Ease out the 2 cables from the clips. Lift off the microfilter housing.

Step 2
With the microfilter housing removed, you have easy access to all 6 spark plugs.

The microfilter housing is surprisingly heavy. It has 2 water drains built in.

Step 3
Remove the 2 10mm nuts at the top left and bottom right of the coil. Plugs 1 & 6 have earthing straps.

Pull up the silver clip at the bottom of the coil with your fingers and gently ease out the connector. Now the coil can be lifted out.

Step 4
Now using your spark plug socket with at least a 6" extension bar, you can remove the plugs and replace the new ones.

I used a high temp spark plug lubricant/ anti-seize compund so I tightened the plugs until just firmly tight. The spark plug torque is 30Nm otherwise.

Repeat the procedure for all 6 plugs and follow the reverse procedure to replace the microfilter housing.

Good write-up.

Originally Posted by WAM

Step 4
Now using your spark plug socket with at least a 6" extension bar, you can remove the plugs and replace the new ones.

I used a high temp spark plug lubricant/ anti-seize compund so I tightened the plugs until just firmly tight. The spark plug torque is 30Nm otherwise.

Repeat the procedure for all 6 plugs and follow the reverse procedure to replace the microfilter housing.

Interesting, they are four pronged....

Originally Posted by drmwvr

Interesting, they are four pronged....

I noticed that too. I assume it allows for a bigger spark which give a more complete combustion of the fuel mixture.

Just used this DIY...excellent job.

Let me just add that after 53,xxx miles, my plugs had virtually no wear. I still replaced them with the OEM NGK's, however now I know I won't ever need to replace them again.

I believe they are truly 100,000 mile plugs.

Wow, I need to do this! Thanks for the DIY.

Will these spark plugs work?

Great write up i did this yesterday using this thread...i was affraid of breaking them when pulling the connector out but with a little force it came out no harm done...THANKS!!

Originally Posted by gfeiner

I noticed that too. I assume it allows for a bigger spark which give a more complete combustion of the fuel mixture.

There is no bigger/better spark or more complete combustion, if there was the MFG would be all over it since more complete combustion would gain lower emissions, more HP and huge tax advantages for pennies per car, it either sparks or it doesn't, no science or data at all to support that 4 prongs are better than 1,2, or 3.

Not to thread crap but its just bad info that gets past around a lot. Kind of like vented/slotted rotors ( with less braking area thus less friction material and correspondingly less braking efficiency) will somehow give better performance. They dont, never have, never will. Its a simple equation, how much surface area do the pads have to contact, take any away and the performance goes down.

One of the biggest waste of your DIY dollars and potentially the easiest to cause significant engine damage is using a plug other than that of the MFG's specs. The best part is the NGK OEM's are a few bucks each. People spend the price of a set of 6 OEM plugs for ONE Iridium or 4 prong or the latest rage plug, ask a mechanic, one you trust, dont take my word for it, he will tell you its snake oil.

Please dont think I'm calling anyone a liar or dumb, there is a lot of misinformation out there and this is something I know quite a bit about. Changing your plugs at 50K BTU is overkill, wasted money, if you can live with that then go ahead., but dont expect any tangible benefit, because you will not get any. You will one day, when the car wont start and after changing the failed plug /plugs then you will see the benefit, no sooner.

Its like a light bulb, it works or it doesn't, there is no in between

so are you saying you only replace your spark plugs when your engine won't start?

On Pelican's DIY page they say to replace every 10k which I think is excessive, but you're on the other end of the spectrum. I generally trust Pelican, though.

Originally Posted by stash182

so are you saying you only replace your spark plugs when your engine won't start?

On Pelican's DIY page they say to replace every 10k which I think is excessive, but you're on the other end of the spectrum. I generally trust Pelican, though.

Ideally prior to that. I would think any competent technician or DIY'r would see the lunacy of changing plugs at 10K intervals. Unless you had serious engine work, track the car, a lot...., or in the case of Pelican, sell plugs.


Take it for what its worth, its a cheap part of any maintenance regime, but it does come with a cost, a risk whatever you call it. If you have never installed a Helicoil insert into threaded head, I would use the money elsewhere.

That's just me, I have been wrong before, ask my ex....

M54 engine E46. BMW recommends plugs @ 100k

I recently changed my spark plug and it's totally different from yours. Mine has a flip switch that removes the connector from the socket. Then I just wiggle/twist the coil out of the socket. There is no nuts or anything to remove. I had all 6 of my coils change under recall though.

Originally Posted by DevHead

Will these spark plugs work?

Worst plugs ever....I had them in my 85 b/c they were listed as "OEM approved replacements" in the AutoZone computer....after about 10k miles I thought my fuel pump was dying. Swapped out to OE (which on mine is single prong platinum, not 4-prong) and it runs great.

Buddy of mine put those Bosch +4 Platinums in his Mustang and had the same problem, and I know a couple guys that have tried them in Jeeps with no success! I'd steer clear

replaced my plugs this weekend. It was super easy, except I had to go out and buy a torque wrench. Surprised how little trouble I ran into other than the PITA to remove the plugs. No more weird idling problems. These Pelican instructions were perfect as always.

Upon a diagnostic check, #2 plug was found to miss. The dealer wanted $440 to replace 6 spark plugs. I was able to politely say no thank you without a snear. Thanks for the detailed write up. It will definitely come in handy when I decide to replace them.

Originally Posted by Dave 330i

Upon a diagnostic check, #2 plug was found to miss. The dealer wanted $440 to replace 6 spark plugs. I was able to politely say no thank you without a snear. Thanks for the detailed write up. It will definitely come in handy when I decide to replace them.

Damn STEALERSHIP!!!!!!!!!!!!!!

Key thing is what is making the misfire? Plugs are rarely the cause. I would guess a coil for the cost and ease of swapping the coil to another cylinder and seeing if the fault follows the coil, why not give that a try first?

Originally Posted by FalconGuy

Key thing is what is making the misfire? Plugs are rarely the cause. I would guess a coil for the cost and ease of swapping the coil to another cylinder and seeing if the fault follows the coil, why not give that a try first?

Yep, I questioned the SA, and he said it was the plug. Of course he will run a test afterward replacing 6 plugs and then tell me it's the #2 coil, and charges me another $200? I don't want to use my time to do diagnostics. Remember, it's hot here in Houston. And, I sweat like a hog. Anyway, the car runs fine now.

Originally Posted by WAM

Step 3
Remove the 2 10mm nuts at the top left and bottom right of the coil. Plugs 1 & 6 have earthing straps.

Pull up the silver clip at the bottom of the coil with your fingers and gently ease out the connector. Now the coil can be lifted out.

yes, these were the pictures I was missing. Thanks.
You have to remove the plastic housing that goes over the oil filler to get to the coils?

Great DYI thread and a real money saver. Just did my wife's 325xi which took about an hour and saved me 400 bucks. One thing I'd like to add is be very careful when removing the coil/boot from the plug. It's tempting to pull on the coil itself but DONT. Use constant, firm pressure and gingerly twist the boot while pulling. Also, when reinstalling it may be a bit disconcerting that you dont hear a "click" or "snap" when you put the boot back on but there's no need to worry......clean the micro-filter while your in there!

Just wanted to say thanks for the write-up!! Replaced the plugs in my '99 323i today, took about an hour, even for someone who has never replaced an engine part before (sad, I know). Dealer wanted CDN $150 just for the plugs! If I might add, the 100k rating on the OEM plugs seems very reasonable- I've got 144,000 km on the car (90,000 miles) and I've just started to have the occasional misfire/sputter while idling, but the car still runs fine most of the time. I'm sure I could have pushed an extra 5-10k out of them, but with a lot of traveling to do this winter, why risk being stranded in the middle of nowhere? Now I'll never have to worry about the plugs again for a very, very long time!