After tracking the squeal in my engine, a mechanic at work seems to think it could be the EGR valve sticking, and therefore no closing properly which in turn causes the pressure squeal.
As he's not familiar with this particlar engine (2004 Astra (H series) SXi), he would like some advice before investigating further.
Could somebody shed some light on this, 1) could this be the possible cause? 2) and How can we clean the EGR valve?
The car performance has been unaffected except at idle, it does start to stutter, and nothing has shown up on the engine managment system,its just getting annoying.