When does car battery indicator lights up?

If the cost of replacing a non-essential part seems exhorbitant, one may choose to "clear" the code by having the computer reset. If the problem reoccurs, the light will come back on. Sometimes the light goes off on its own — this indicates a "soft code", which usually refers to a temporary non-serious problem. Even though the emission system typically does not affect anything more than gas mileage, problems will trip a "hard code", requiring a reset. One can attempt the reset themselves, either by removing (and reinserting) the proper fuse, or by temporarily disconnecting the battery. However, this will not work on all vehicles, and disconnecting the battery may reset other systems as well (such as the idle). Alternatively, one may cover the MIL with a piece of black electrical tape or remove the bulb for the Malfunction Indicator Lamp if you wish to continue driving your vehicle with a potentially major problem. When the car no longer starts, you will not have to worry about the light. In the states of CA, MA and NY, vehicles with the "check engine" light on will not pass annual inspection.