DB9 Top Gear Track
AO Silver Member
Join Date: Jan 2007
Location: United Kingdom
County: East Sussex
A duff battery can indeed cause all sorts of problems however I wouldn't change it as a matter of course, the engine management light can come on for a whole host of reasons.
Providing the car is starting and running OK I recommend you either invest in a cheap OBD reader or software to read the codes. You may well find the problem is nothing to do with the battery.
MultiECUScan (google it) is a fine piece of software and the free version is good enough for what you want, you need a special cable to connect to the car's ECU, which is a socket behind the panel by your right knee.
You can also buy Bluetooth bits of kit that plug into the socket and you use an app on your mobile.
Loose - not close, compact, or tight in structure or arrangement
Lose - to part with or come to be without, as through theft, accident, negligence, etc.