This week on Car Talk, all was well with Karen's Honda until her boyfriend gave it a tune-up-- which promptly turned on the Check Engine light. We'll just skip past the question of whether he messed up, and go right to trying to figure out what he messed up. Elsewhere in Civic-land, Anna came out of work one day to discover an unwanted passenger in her car: a white rat. How did it get there, and how can she ever go near her car again? Also, our Physicist-on-Call Wolfgang checks in to help clarify, and de-bogusify, Ray's "dispersion" theory on the odd behavior of a keyless remote; and is Lara's starting problem really caused by her turning the key too fast? All this, and lots more, this week on Car Talk.