Analysis

Sand the sunroof lid panel lip at the seam to determine the corrosion depth. Use a sander with aggressive grit such as 36 or 40 grit sandpaper. Sand no more than 0.75 mm (0.03 in) from the area with the heaviest corrosion. If you are able to completely remove the corrosion, proceed with the repair procedure. If any corrosion remains in the seam between the inner and outer panels, replace the sunroof lid panel.