What causes a spark plug to get carbon fouled?
What causes a spark plug to get carbon fouled? Rich Fuel Mixture A rich fuel mixture can result in carbon fouling. There are several potential reasons the fuel mixture is rich and these reasons range from a leaky fuel injector to problems with vehicle oxygen or coolant sensors. Can a coolant leak foul the spark plug? Modern coolants do not cause this type of buildup quickly due to the reduction of phosphate, zinc and other additives that can contaminate the catalytic converters. Unfortunately, it also means that drivers will run a vehicle with a coolant leak for several thousand miles...