There is no definitive answer to this question as it can vary depending on the make and model of the engine in question. However, some people believe that bank 1 is typically the front-left side of the engine when looking at it from the front. Others believe that bank 1 is typically the front-right side of the engine when looking at it from the front. Ultimately, it is best to consult your vehicle's owner manual or a qualified mechanic to be sure.