has been on for last week. It started right after I put a bottle of Techron injector cleaner in the car and the other thing I notice is when I get on the car it kind of feels like it is pulsing back and forth. It feels like something is holding it back and then let's it go....does that make sense as far as a description. The car also pings a little as well. Any ideas? TIA. Oh I am taking it in tomorrow to Audi for an oil change will they hook it up to computer to see what check engine code is?