If you are investigating a battery that is flat after parking, save every stored and pending code before clearing anything. A proper parasitic-draw test needs a suitable meter and vehicle-specific procedure. Record the engine temperature and load alongside the reading; the same value can mean different things in different conditions.
A basic reader may not access every module. Check that lamps and accessories switch off; modern modules may need time to enter sleep mode. Use the exact vehicle’s service information to interpret the result.
Quick educational note
For information, not a diagnosis or repair instruction. Vehicle-specific checks are still required. Consult the manufacturer's guidance and a qualified technician.
How to use this information
This article explains general principles and does not establish what is wrong with your vehicle. Read the content limitations.