You probably know that when the Check Engine Light (CEL) illuminates in your vehicle, you should bring the vehicle to the garage to see what is wrong. When you do this, the first thing your mechanic does is plug in a code scanner to “read the codes”. A code scanner interfaces with the vehicle’s Powertrain Control Module (PCM) where all engine error codes are stored. This allows the mechanic to professionally diagnose the issue and solve it. Since 1995, cars have been made with OBDII ports that allow scanning PCM modules.












