Fault codes

sorry all, I thought I reply using my phone but looks like it didn't go through properly.

Have been to the dealer and he read the codes.

P0238 Turbe pressure. (downstream of heat exchanger ) short circuit to positive or open circuit

P0341 Camshaft signal. no signal or signal incorrect

the engine management light or the message haven't appeared since the 24th Jan.

if anyone can shed any light on this please let me know, I appreciate your help

cheers
Helen