Car was shoddy to start , VCDS showing glow plugs open circuit and cam shaft sensor implauseble sihnal and battery was going flat. Replaced battery and it starts first time every time. VCDS still showing same codes. My question is could a tuning box (chips express) be causing these codes as car is fine and battery drain is gone ?

Sent from the depths of hell

take the box off, clear the codes and see if they return?

The Pdi  engine will nearly always start without the glow plugs working,unless the ambient temperature is very low   however,the glow plugs are meant to stay on after the engine starts for at least 60 seconds as an aid to lowering start up emissions so the ecu send the instruction for the glow plugs to come on post ignition then flags up codes when the glow plugs resistance is out of speck due to being worn out PS the BXE engine is fitted with 5 volt glow plugs on newer years ! i very nearly fitted the wrong ones