Spark plugs use an electrical charge from a vehicle's battery to create combustion, allowing a motor to run. These parts go bad after a relatively short period of time, and must be replaced several times during a vehicle's life. Accessing and replacing the spark plugs on a 2005 Scion xB is very straightforward, requiring only a few basic tools and 15 to 25 minutes of your time.
Park your Scion in a location where the front of the vehicle can be easily accessed.
Open the hood and use a Crescent wrench to remove the negative terminal from the vehicle's battery.
Locate the four spark plug wires coming off the top of the motor casing. If the stock wires are installed, they will be colored gray. Remove all of these by gently pulling them off. The are clipped onto the top of the plugs.
Use a spark plug wrench to carefully remove all four plugs.
Slide new spark plugs into place and tighten them down. Be very careful not to cross-thread these.
Press the spark plug wires down onto the plug heads. The wire will click when it clips into place.
Replace the negative terminal on the battery.
