If the battery is the original it could be as simple as a new battery being needed. A battery at the end of its life can result in many fault codes coming up.
However, if the battery is fine then my first port of call would be to check the EGR valve. Could well be clogged up and require a thorough clean-up or even replacement with a new one. The EGR valve clogging up is quite a common fault, especially if most of your journeys are short ones.
ChicksFan
April 2011