Spark plug replacement DIY
 

My 2012 A6 3.0T is out of warranty and, thanks to learning on my previous car (2002 A4), I've decided to tackle as much of the maintenance as possible. I'm approaching 55k miles, and that service is one of the big ones. Included in that is replacement of the spark plugs. I know there's a writeup or two in the B8 S4 forum, but I haven't seen any specifically for the C7 A6, so I figured I'd have a go at it.

I spent a couple hours on the Audi "erwin" site and downloaded all of the relevant repair & maintenance manuals in PDF form - not bad for $35 as long as I'm not missing anything. They seem pretty comparable to the level of detail in the old Bentley manuals.

On to the job!

I started with the passenger side. First I loosened the clamps on each end of the air intake tube and removed the end connected to the filter box and moved it out of the way. That gives enough clearance to access everything easily.

https://cimg1.ibsrv.net/gimg/www.aud...83ce7339be.jpg


I then removed the 2 torx screws holding the coil pack harness down, unhooked each of the connectors, and slid the whole harness down and off the coil packs.

Removal of the coil packs themselves was a bit tricky, only because they were stuck in there pretty good. I didn't have a removal tool, so I used channel lock pliers on the red casing and pulled straight out. I replaced each plug one at a time so I could keep track of the condition of each plug, just in case I found one that looked unusual. Fortunately, they all looked identical:

https://cimg0.ibsrv.net/gimg/www.aud...ce5d55f81a.jpg

I used OEM plugs as replacements, using anti-seize on the threads and dielectric grease on the inside lip of the coil pack boot as instructed by the manual. Tightening torque is 30 Nm, or 22 foot pounds.

The driver's side was a little trickier because the coolant reservoir needs to be moved in order to get clear access to the coils/plugs, but the main coolant hose on the bottom doesn't provide much leeway. I unscrewed it from the bracket and disconnected the level sensor on the bottom. I was able to move it enough forward and to the side to get sufficient access - not as good as the passenger side but good enough.

https://cimg1.ibsrv.net/gimg/www.aud...ae3455c597.jpg


I also unhooked the clip that holds part of the coil pack harness to the head in order to get more slack in the harness.

https://cimg7.ibsrv.net/gimg/www.aud...afc95ba9f8.jpg


Overall, the job was very straightforward. I estimate it took me about 1.5 hours, mostly because this was the first time on this car.

Hope this is helpful to someone... Next up is the accessory belt!

-Mark

Looks great, I'm about to do the ones on my 2010 A6. Same procedure and overall should be a snap.

Nice write-up! Are you replacing the supercharger belt yourself too?

coil removal
 

if no tool

I've seen people use 2 plastic tie belts wrapped around each end to pull up on

Yes, although it's not due until 75k I think. Oddly, the SC belt has to be removed in order to replace the accessory belt, so I'm tempted to do both...

-Mark

Hmm, not too sure about that. My tech had said it was the front supercharger belt that calls for replacing at 55K. In the 2012 Audi Maint Schedule, it says replace front V belt for compressor drive at 55K for A6 3.0T.
Let us know if you learn otherwise..

Thanks for the DIY.

What kind of plugs are recommended for supercharged engines? What were the OEM plugs? I prefer Bosch or NGK platinum or iridium single electrode plugs for NA engines.

Yes Nice write-up. When I replaced my plugs, the hardest part for me was snapping off the coil pack connectors as I was afraid to break any clips. I agree, overall pretty easy. I did have the benefit of a friend helping me move the coolant reservoir out of the way as needed for driver side plugs. Second time is easier = )

My personal opinion on plug types. Stay away from platinum plugs on any boosted application. Just my 2 cents being I've been tuning SC engines for years. Get more risk of knock as platinum tends to absorb heat more than copper.

On plugs, I did bring up the question and got some good information.
https://www.audiworld.com/forums/a6-...0tfsi-2884529/

I went with stockers as my replacements. Maybe this weekend I'll carve enough time to drop them in if I'm not on a trip to Long Island

Bill thats a great post thanks for sharing. Very good point that i forget most just want longevity and ease of maintenance, so the platinums are preferred in that case.
i just happen to be an odball that likes working on my car and dont mind replacing plugs sooner. = )
"Scotty i need more power" lol.

The OEM plugs are NGK's. I stayed with OEM only because I didn't feel like experimenting...

As for the belt... I'll admit I'm confused. I know I had found some info in the past that specified different intervals for the 2 belts, but the maintenance book is clear that it's the front belt (which I now know is the SC belt) is to be replaced at 55k... Can't find anything on the rear (accessory) belt. Well... I guess I'll be ordering the SC belt and doing them both then! :-)

-Mark

Ah, I found it... it seems I had them swapped. The accessory belt is due at 75k. Confusing, as the maintenance schedule describes both as "ribbed V-belt". Oh well...

-Mark

Fantastic instructions. I am having issues getting the coolant reservoir sensor removed. Any special trick since can't see the bottom of the clip? Cant move the tank without unclipping it and see yours was off. Thanks

Many of those connectors require a push first then pull as you are holding the lock.

This. I always end up doing a push-pull dance trying to get these connectors to unlock. And this one is a bit stickier since it gets a lot of the water splashed up from the bottom of the car. Move the reservoir the best you can to get the best view/grip before trying to remove it, then move the connector around to break it free from any dried dirt that might be holding it in place. I hate that they require so much force sometimes...

-Mark

I had these pictures saved from one of the DIY threads...

Spark plug coil removal tool
Attachment 72415
http://i17.photobucket.com/albums/b7...psom2jwgno.jpg

Out of curiosity, when are you changing the spark plugs? I know the service is recommended at 55K according to the manual, but I figure the original plugs must be iridium and they should last 100K?? I have a 2013 3.0L A6.

Spark plug changes are based on actual conditions that vary based on individual driving patterns and unpredictable related component failures.


If fuel injector performance changes... spark plugs will foul at different rate.
If O2 begin to fail.. performance of spark plugs will differ.
If dramatic temperature difference is measured... the AFR will change required performance of spark plugs
If altitude or Barometric pressure changes... spark plugs will fire differently.
If fuel (based on previous mentioned changes) is different, AFR will change the way fuel ratio is ignited causing different ignition patterns on plugs.
The various metals in spark plugs retain heat at different levels. Spark plugs made of metal that retains heat longer (harder to dissipate) are horrible for forced induction engines as they create detonation and reduced timing.
I.E. platinum and iridium retain heat longer, and bad for forced induction. Copper plugs don't retain heat as much and are better for forced induction engines to reduce detonation and improve timing curves.

Nobody panic!!! just my 2 cents

How did you get the lower torx bit off (on the passenger side closest to the air box). I can't seem to get my torx driver in there without having to take the whole airbox out.

If your driver is a little longer, you can take the cover off where the air filter sits (perpendicular to the car). That'd give you more room, I believe its just two plastic screws holding it in

See here for reference

https://cimg1.ibsrv.net/cimg/www.aud...-10-150833.jpg

Successfully changed plugs! I removed the air tube and the holder for the air filter and had just about enough room to get my 1/4" ratchet and T20 torx bit in there. Was a little tight but came out easy.

On the driver side, once you move the coolant bottle, it was pretty easy. Just need to maneuver the coolant bottle around a bit. The only "issue" i had was leaking coolant out of one of the disconnected hoses, I grabbed a helper and had them hold it upright so it wouldn't leak.

not sure if this will help but just did my plugs last weekend. Car idles much smoother but getting the coil packs off was ridiculously difficult. I did find that using a 1" wide strap looped under the bottom of the connector on the pack allowed me the grip needed to pull them out. Just be careful when pulling as when they let go you don't want them flying out of the engine compartment.

I purchased the audi/vw coil puller so wasn't too hard to get them out (but man do they require a good amount of force).

Next day after replacing the plugs.. holy sh** the car idles so much better and the throttle response is way better. I would have replaced mine at 45K instead had I know the power loss I was getting.

Coolant Level Sensor Connector
 

Bill:
Thanks for the post. You've inspired me to give it a try. Hardest part to me seems to be figuring out how to disconnect the coolant level sensor connector without breaking it so the tank can move over a bit more. What's/where's the magic push or pull thingy that releases the connector?

There is some little lever on the connector you have to press IIRC...

That engine is cleaner than my just washed beer mug !!!!!! Nice.

I'm almost at 50K with my recently bought 2013 A6 3.0T (still on CPO warranty). Idling has been a bit interesting, with frequent pulsations (small dips in RPM's) that are driving me crazy. Audi service technicians said it is normal. I had them check the engine mounts and they claimed that everything was ok.

I am wondering if changing the plugs would help with this slight vibration/pulsation issue?

Is no one concerned with the rubber seal/gasket that is basically destroyed when we remove the ignition coils?https://cimg3.ibsrv.net/gimg/www.aud...0be519cef8.jpg
https://cimg9.ibsrv.net/gimg/www.aud...0a3f298025.jpg

Changed mine few weeks ago and noticed the same. Dont even know there the damaged seal is coming from. Installed the new spark plugs and they work as intended.

Weird, @fEArmW and @hippithe. Mine look just fine (I have 109K miles on the car).

Thanks go to @a44mark for the writeup. Worked like a charm for me this weekend.

This torx mount for the coil pack rail on the passenger side nearest the front of the engine was a bear. Need a low-profile ratchet/torx drive to get to it since the airbox is in the way. @kevrhoff, I was not able to understand your pic since it's from a different car.

https://cimg5.ibsrv.net/gimg/www.aud...06bdc30685.jpg

How to remove sensor from bottom of Coolant reservoir?
 

I didn't remove the sensor, just the electrical connection. There a picture of the reservoir bottom side in my thread.

https://www.audiworld.com/forums/a7-...hange-2917832/

How do you disconnect the electrical sensor from the bottom?
 

I can't figure out how to remove the electrical connection from the bottom of the tank. Don't want to push too hard and break it. Is there a latch or something?

Lol, there is a trick, google "vw auto electrical plug"...

YES!!!! You are the man. That thing was driving me nuts!

Thanks for the write up
 

Just did my own 55k service. The write up for the plugs was very helpful. Used two tie bands, one on either side of the coil pack, to pull them. Worked great!

Regarding the coolant bottle, it seemed easier to me to just unscrew the mounting bracket than mess with the sensor. Two torx screws. And a little bungee to hold the bottle out of the way. Plenty of room to get at the harness.

All in all, a pretty easy job thanks to the great write up. Thanks!

Hi, bit late to thread here, but, can anyone guide me where to purchase a couple of the torx ignition rail mount screws as shown in the above pic? I even tried the dealer who couldn't locate it on the parts breakdown schematic. Thanks.

I would just try to use a regular screwdriver that will fit snugly on the torx screw. They aren't very tight. I didn't have the exact torx driver, but was able to use a different size to get the job done.

Take one off from other rail and bring it to Lowe's or Home Depot. You can match up a metric screw there. Doesn't have to be Torx head.