2014 500L with almost 90K miles. I'd had a check engine light on for a while (turbo under-charge fault code) decided to replace the spark plugs and wha-lah the engine light went out AND my cruise control was back to functioning normally. However I noticed that one of the coil pack had a break at the wire connection/plug in. I could just pull it off so I put the "plug" grease on the contacts, well that seems to no longer be doing the trick.
Do I need to replace all 4 coil packs or can I just replace the broken one? Rock Auto sell them for 25 bucks@ plush shipping, the NGK brand is slightly more, but saving a bit of cash is appealing