2002 bmw 540i check engine light
Buy an OBD 2 scanner, or a less expensive OBD 2 code reader (OBD means on board diagnostics, 2 means second generation-anything built after 1996, generally). Plug into your car's diagnostic port and read the codes. The trouble codes relay what the computer detected as a problem-points you to a course of action. Whether you fix it yourself or take to a shop with the codes for the repairs.
Many national chains, such as Autozone, will do scans of the engine computer for free, hoping you will return there to buy parts. Be aware a trouble code does not relay a specific course of action-it only points you or a technician to what the computer saw as a problem, like a circuit failure in a sensor signal, it could be the sensor or the wiring associated with it. Common sense and a knowledge of how the many components and sensors work and interact will help one understand and find the problem. For example, a code of a bad oxygen sensor signal-reading too much oxygen in the exhaust-would not be a bad oxygen sensor, but one needs to check why the air-fuel mixture is wrong-too lean-is a vacuum line leaking, or is the fuel pressure too low-these are the types of questions that can arise from a trouble code.
If you want to avoid mechanics entirely, better buy a repair manual and learn all you can about modern engine management electronics.
2002 BMW 5...
on Mar 17, 2013