[larchamb]

Hi all,


Ill start with its a 2013 BRZ ive owned the whole way, 45k on it. Driving back from hockey one night the check engine light came on. Dutifully I went to the dealership the next day, they said something about an issue with engine imbalance and they would need it for a full day and I could drive it the few days in between. They have now had it for 1.5 days and called me to say its running "better" that the spark plugs were fouled and then questioned if I had been putting premium in. I have only EVER filled up with Shell V-power, which is 91. They are going to keep looking at it.
I'm not exactly a gear head, so any help understanding what is going on would be much appreciated. I am worried in general about wtf is going on, again since I have only EVER put 91 into it. Should I be concerned about other possible related issue, now and down the road, and is there anyway to gather evidence from the car that I can go after the dealership for faults or even Shell for faults.
I have occasionally switched between sport modes, and its an automatic fyi.
Thank you in advance.