Q: Car won’t start but engine, battery, and oil light comes on.

If you think your battery has gone dead again, it could be that the alternator you bought isn’t any good. If you are buying from one of the big retail parts chains, I’d say you stand a 30% chance of getting a bad one. The only way to be sure is to do a proper charging system test. If the engine is cranking but will not start, that’s another issue. The best first thing to check in that case is for air leaks. any rubber hoses or boots that are off or in bad condition can cause the car not to start or to run badly. Beyond that, you will need to run a proper diagnostic including reading any stored codes in the engine computer.To get that done at your convenience, contact YourMechanic. They can send a technician to your home or office to check out your Focus and let you know what it will take to get going again.