A Hyundai Sonata's crank sensor might need to replaced if the car begins to stall or misfire. The crank sensor is a small sensor that tells the Sonata's spark plugs when to fire. The sensor is attached to the bottom of the vehicle's engine. It includes three wires connected to the back that should be marked before removing them in order to keep track of where they reattach to the new sensor.
Jack up the driver's side of the Sonata and slide the jack stands under the frame. Set the car down on the stands, with the stands resting directly beneath the frame.
Slide under and locate the the crank sensor. It is attached to the bottom side of the engine on the driver's side on your Sonata. It will also be the only plug-looking device, with three wires running from it.
Remove the mounting bolt that holds the sensor in place. This bolt can be removed with an open-end wrench.
Mark the three wires with paper showing which wires connect to which terminal. One terminal will be positive (+), one is a ground wire and the other is the sensor's feed wire, which runs back to the Sonata's power control module. The wires' colors will vary between different years of Sonatas. Remove the wires from their respective terminals with a Philips screwdriver.
Reconnect the wires to their respective terminals on the new sensor.
Hold up the new sensor and thread the mounting bolt back in place by hand. Tighten it with a wrench.
Lower the Sonata down from the jack stands and jack.
