How can I remove soot stains from a light grey carpet?

Answer: Use BISSELL Tough Stain Precleaner™ on heavily soiled areas before using a BISSELL Deep Cleaner.
Generously and evenly spray the area with BISSELL Tough Stain Precleaner™. Gently work the solution into area with a small brush, sponge or cloth using light strokes from the edges of the stain to the center. When you reach the center of the stain, lightly pinch in an upward motion. Do not rub the stain. Wait 5 minutes.

Use your upright deep cleaner to clean the soiled area with one of BISSELL’s 2X deep cleaning formulas in your favorite scent. If you are using your BISSELL Little Green® or SpotBot® portable deep cleaner use BISSELL 2X Little Green Formula. If any hint of discoloration remains, apply OxyPro® Stain Remover for Carpet.