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: June 25, 2018
The car battery itself may be the cause if it has corroded cable terminals, bad wiring, damaged cells or plates inside or if it is leaking electrolyte. This article refers primarily to conventional vehicles with conventional 12-volt batteries; more electrified vehicles and those higher-voltage electrical systems will vary. The charging system warning light should show for a few seconds when you start the car, but if the battery light shows while you're driving the vehicle, that light signals a problem. Among other signs that the alternator or other parts of the charging system aren't working are dim headlights or the clock losing time.
Engine deposits caused by low-quality or contaminated gasoline create drivability problems, and the cure for that might be a fuel system cleaning, either by a repair shop or with a gas-tank additive. An illuminated check engine light signals when something is amiss in the emissions control system, but depending on what the issue is it could also affect fuel economy or engine performance, so don’t ignore it. A faulty oxygen sensor, for example, leaves the engine computer in the dark about how to set the air-fuel mixture, and that can result in poor fuel economy.