P2000 code and ISO9141

This is a fault relating to an emission's control device called a Nitrous Oxide Trap. As on petrol engines there is a catalytic convertor, clean burning diesel engines need to remove the nitrogen gas from the exhaust gasses. Like any filter (even catalytic convertors), they can only absorb so much before they are full and need to be replaced. NOx Trap is relatively new technology.

ISO9141 is not a fault code- it refers to the communication system that your vehicle uses to relay info to and from its different computer boxes. Also a relatively new system, it is a CAN communications network that can transfer info and receive simultaneously, hence speeding up response times. This technology is critical in safety specific items such as ABS braking and Airbags as the faster you can get the unit to respond, the more efficient the system is.