dd13 410hp s/n 02BC3501 unit had issues with no fuel pressure on doser sensor. check and stop engine lamps on. replaced fuel block in lhs rear and doser block and nozzle at turbo down pipe. read data and found pressure on sensor at 30 psi. unit has surging idle with fuel pressure ranging from 3400 to 6500 psi at idle. ideas on what to look at in lap top to help with diagnosis codes have not returned as of yet.