My roommate bought a lemon (2003 Mazda 6) that stopped working once the summer was over. I'm not talking about cold start issues, this thing always cranks but won't turn over unless engine compartment is 80+ degrees...

​​​​When the weather is 75 or less the AT, TC, and TCS lights stay on and the throttle body is disabled somehow. If I use a heater under the hood to warm things up the lights go out like normal and I can hear the throttle body open and close. It always starts then. As soon as things cool down, just a bit, the lights stay on and the throttle body doesn't move anymore making the car impossible to start. I can't figure out what sensor could possibly cause this... I checked fluid levels thinking they expand when hot just enough. Maybe the computer itself? Please advise. It's hardly worth the cost of diagnosis and repair at the dealership. I just want him to be able to sell it and get it off my property.