As part of the ignition system, the distributor cap on your Nissan Sentra is designed to route the electrical voltage to the spark plugs in sequential order to allow the engine to run properly. Some of the caps, designed for the Nissan Sentra developed a problem with ignition arcing which would prevent it from firing correctly, causing it not to start or run very rough. To prevent this problem, you can replace the cap yourself easily in about an hour.
Locate the distributor cap on the driver's side of your Nissan Sentra, secured to the engine block. It will be a black cap with spark plug wires running from the spark plugs to the cap.
Undo the screws that are holding the distributor cap in place on top of the distributor, leaving the spark plug wires in place. Pull the cap straight back when it is loose.
Set the cap off to the side with the wires still attached and locate the rotor that was underneath the distributor cap. Unfasten the screw that is holding the rotor in place and slowly take the rotor off the distributor, noticing how the rotor was positioned on the distributor.
Place the new rotor that came with the new distributor cap on the distributor, positioning it exactly the same way the old one came off. Secure the new rotor by using a screwdriver to tighten the screw on the rotor.
Locate the number one that is stamped on the new distributor cap and take the number one spark plug off the old cap, attaching it to the new cap on the number one post. Position the new distributor cap on top of the distributor exactly the way the old one came off.
Secure the new distributor cap to the distributor by tightening the three screws on the cap with a screwdriver. Transfer the remaining spark plug wires to the new cap, being careful to put them in the exact location of the old cap.
Start the engine of your Nissan Sentra and verify that the distributor cap is working correctly. Once you are satisfied, shut the engine off.
