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 DIY Spark Plug Change

impee's DIY Sparkplug change for BMW 318i e46
How to change Spark Plugs yourself!

Difficulty Level: Easy

Approximate Time For This Project: 1hour

Prices: Professional labour costs for Spark Plug change - £55 (private) or £155 (BMW)

Spark Plug NGK Part number: 12120037607 Part #3. BMW 4 £41.00 
Bosch Super 4 Spark Plugs 510
Original BMW Plugs are NGK, however the Bosch appear to be more or less the same in performance. 1 £22.00
Socket Wrench /
Torque Wrench
It is recommended to use a Torque Wrench to avoid damage to the drain plug.
For more details, please refer to this page. 1  
Socket Wrench Extension Bar A long one, about 9"   1 £3 
10mm Spark Plug Socket  1 £5 
Torx 30 Bit See section #3   1  
Flat Head Screw Driver     1  
CelloTape Sticky Tape, Insulation tape, any tape you want! (optional)   1  

*prices correct at time of publication

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1) Assemble Your Kit + Notes

Below is the total kit I used to change the Spark Plugs for my BMW e46 318i. Mind you.

I used NGK Spark Plugs, however the Bosch I mentioned are the best of the Bosch line of spark plugs and are fine for more or less any other car, however there are different versions of this same Spark Plug. The version number depend on the gap of the Spark Plug as each car requires a different gap for the ideal spark to be created. My car is a 318i e46 N42 2002 2000cc 4 Cylinder takes version 510, however do double check this with at the shop before you buy them.

Change Duration: Sparkplugs should be replaced every 20-30,000 miles.


2) Engine Photograph - Illustration

This photograph shows the engine with all the covers still on.

The order in which covers and components are meant to be removed is illustrated below i.e. 1, 2,3 & 4. This order must be followed to allow easy access to the Spark Plugs.



3) Remove the Pollen Filter Cover & Casing

1) First Remove the Pollen Filter cover by turning the 3 small knobs (anti clockwise) as identified at the bottom of this photograph and then pulling it the cover outwards. Then remove the actual Pollen Filter.

2) Next use the Torx 30 Bit (as shown below) and remove the 4 securely tightened screws as identified at the top of the photograph, then remove the large tray beneath them.

Note:  Twice I have dropped a screw down the void at the back while fitting them back, so be very careful when you do it.

Hexagon Bit

3) Next unclip and loosen the hoses running across in the middle, otherwise the tray will not come out.


4)  Engine Cover - Removal

Next remove the main big BMW cover (Intake Manifold) at the front of engine (#2 in section 2 photograph) using this method:

1) Remove the 2 clips at the front - pull up and then out the small round black pins (expanding rivets) with a flat head screw driver

2 ) Un-clip the hook on the top left

3) Remove the large hose on the top right

Removing BMW engine cover


5) Remove Oil Filter Cap

Remove the oil cap by squeezing it on two sides and then pulling it up (as indicated on the cap itself).


6) Spark Plugs Casing Cover

Next remove the cover underneath the oil cap by simply pulling it up to release it from small clips holding it down.

Next put the oil cap back on (from where it was removed) to avoid "any" dirt getting in to the oil chamber. 


7) Spark Plugs Cover

As you can see below there are 4 Spark Plugs. Each of them is covered by a small rectangle cover (Plug Fastener) with wires attached to it.


1) Put your finger into to clip hole (Locking Mechanism) and raise it up and pull. This will release the Locking Mechanism.

2) Next pull the cable (Socket Housing) away to disconnect it from the Ignition Coil.


3) Next turn the Ignition Coil a little to the right and then put you finger back into the clip on the and pull it up to raise the Ignition Coil. I was able to pull 2 of them up rather easy, but 2 were a little stiff. If it is stiff, then rotate it left and right while pulling it out of the hole.

Ignition Coil


8) Swap Spark Plugs

1) One you have removed the Ignition Coil , check for any dust / dirt in the hole. If you see any (I had quite a bit dust) use a dust blower to blow it out or a narrow vaccum cleaner extension, or using a drinking straw attached to the vaccum cleaner hose.

Note: Blow out the dust before you remove the Spark Plug!

2) Next use the Wrench with the extension bar and the Spark Plug Socket 10mm to remove the Spark Plug. You might want to use some tape to fix the socket to the extension bar, as the socket has a rubber cushion in side it and normally attaches itself to the Spark Plug and when you pull the bar out, and stays in.

As the car is cold the Spark Plugs may be really tight, if so, then you could start the car and let the engine warm up a bit, this will loosen the tight Spark Plugs and you should be able to remove them easier, but then you may burn yourself while changing be careful!

Remove the old Spark Plug

3) Next place the new Spark Plug into Spark Plug Socket and then lower it down into the hole. Tighten the Spark Plug to a hand tight finish - meaning just keep turning it till you need to apply some pressure, at which point stop.

4) Next ighten the Spark Plugs using either of the tools and methods:

1) Using a Torque Wrench, tighten the Spark Plug to 30nm (as specified on the box of the NGK Spark Plug)
2) Or using a Socket Wrench and give the Spark Plug a final tight 90 degrees turn (as specified on the box of your Spark Plugs which depends on the seat of your Spark Plug).  Do not under or over tighten the Spark Plug, this may have an effect on engine performance.

source Bosch


5) Lower down the Ignition Coil and firmly push it down into place over the Spark Plug. Then push back in the wire socket at the top and lower the Plug Fastener clip. Now again push down the once again to ensure it is fully back in place as some times they appear to be fitted, but are not.

1 Plug done!!!

Now repeat this process with the remaining Spark Plugs.


9) Assessment

Next assess your old Spark Plugs and match them with the different type of Spark Plugs as specified in this document. This will help you diagnose any potential issues or problem with your engine.


10) Take Your Car For A Test Drive - Feel it Fly :)

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DIY BMW e46 Spark Plug Change by - impee

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