i had a freind chq my engine lite and he said it was code 380 glow plugs? ,he then erased it ,it did not come back on yet ,i am taking it to a dealer in 2 weeks do you think it will come back on ,if it does not does that mean it has corrected itself or he just erased code ,will dealer see old code stored thanks ,still a beginner at this thanks

if there is a problem with the glow plugs it will come back on and the dealer will see it. If its a hard code it will stay there till the problem is fixed.