It's a defective Igniter Spark Module. Please give the model number so I can locate your correct parts. This is a easy repair on most models. The sparker is sparking, the most likely cause is a defective capacitor in the spark modual. Spark moduals are not repairable and must be replaced.
Another possibility is moisture during the cleaning process found it's way onto one or more of the switches. Excessively wet sponges or cleaning cloths allow water to get onto the switches, which will cause this problem, if applicable.
If this happens to be the case, then remove everything on the stove top and lift the lid, if applicable, since not all stoves have liftable top lids. Remove any clear plastic covers on the valve stems, if applicable and pass warm air over the switches using a common hair blow dryer.
Another cause could be reversed electrical polarity. The plug end will have 3 prongs. It must be directly connected into a properly wired and grounded wall recepticle. Reversed electrical polarity over a long duration of time will destroy the spark module.