When it starts leaking or stops working.
One that stops you car from working.
it stops working
your car is broken
Car overheats, your heat in your car stops working
the car stops working
The drive belt is too loose. Tighten the belt. (but not too tight!)
The Paris Metro starts working at 5:30am and stops at 1:15am. On Saturdays and holidays, it stops at 2:15am
If you back up and hit the brakes and the car stops running, this is likely to mean that the car is not working properly. It is most likely to mean that the fuses are going out.
Inside a crop circle any electronic device mysteriously stops working and why you step out it starts working. At least that's what scientists say.
It sounds like the EGR valve.
Bad battery, most likely.