Q: Service Engine Soon light is on in 2003 Chevrolet Discovery

Code P0327 stands for knock sensor bank 1. Some of the common causes for this code are: a problem at connector C627 or C636, a problem with the power train control model (PCM) or a problem with the knock sensor itself. Code P0134 stands for lambda upstream catalyst bank 1. Some of the common cause for this code include: a problem at connector C635 or C644, a problem with the PCM, or a problem with the oxygen sensor. Code P0441 stands for evaporative system/ incorrect purge flow. The most common cause for this code is a faulty EVAP purge valve. These codes could be related or they may be separate issues. A trained mechanic, such as one from YourMechanic, can inspect your vehicle and determine the exact causes of your Service Engine Soon Light.