yeah, funny story about that. i threw a P0304 earlier this year. called the dealer, told them what was going on, then drove an hour and a half one-way... pointed out the obvious - plugs, coil packs, carbon...
they changed plugs and packs, reset the fault and sent me on my way, many dollars lighter.
a month later the light comes back on, same code.
i call them and ask for a quote on carbon cleaning. they say they can't quote it without seeing it. like a dumbass, i take my car back down there and get a rental. they call me the next morning, say it's full of carbon and they can clean it for $1200+. i told them to button up the car and i'd pick it up that afternoon. in an effort to thoroughly enrage me, the service manager somehow manages to come down to $900+. i asked if he was only going to clean 3 cylinders.
so six hours of driving later, and $140 in the hole for "diagnostics" and a rental car, i'm back home.
long story longer, i found a local guy who was highly recommended for foreign cars, and he did it for $300. he also said he's going to build a walnut blaster for the next time, and for all the other cars that will be having carbon issues...
