Although replacing a battery in a Volkswagen Jetta is an infrequent occurrence, it will eventually happen if you own the car long enough. The Jetta and VW Golf employ a similar procedure for the battery removal and replacement. Before disconnecting the battery in the Jetta, be sure to use a computer memory saver if the vehicle is equipped with a theft-deterrent radio or car alarm system. Otherwise, you'll wipe out the security code, and the systems will remain inoperable until reprogrammed.
Plug the 9-volt battery into the car computer memory saver and then plug the saver into the power source or cigarette lighter socket.
Remove the ignition keys from the Jetta.
Put on the safety goggles and then open the bonnet and locate the battery box cover. It has a light bulb insignia stamped on the top of it. Remove the four screws of the battery box cover with a ratchet and socket. The box casing is two pieces. To separate the pieces, twist one side slightly down and the other slightly upward.
Remove the battery casing bolt located in the front centre with the ratchet and socket.
Remove the battery hold-down bolt using the ratchet, extension and a socket.
Loosen the retaining nut on the negative battery terminal clamp using the ratchet and a socket. You do not need to remove the nut: just loosen it enough to allow the terminal clamp to wiggle off of the battery post. The negative battery terminal is indicated with the black wire and a negative slash "-" stamped on the battery housing.
Loosen the retaining nut on the positive battery terminal clamp in the same fashion. The positive battery terminal is indicated by the red wire with a plus sign "+" stamped on the battery housing.
Slide the battery slightly forward to release it from under the rear retaining lip. Remove the battery and battery insulation cover if applicable. Place the battery insulation cover onto the new battery before installation.
Use the wire brush to clean any noticeable corrosion inside the battery tray. Use the battery terminal/post cleaner tool to clean the battery terminal clamps.
Insert the new battery into the battery tray and reverse the procedure to reinstall it. Be sure to push the new battery back under the retaining lip at the rear of the casing. Also be sure to attach the positive terminal to the battery first and the negative last. Before replacing the battery casing cover assembly, spray the battery posts and terminal clamps with anti-corrosion battery terminal spray.
Start the Jetta to ensure proper operation and then remove the car computer memory saver. Remove the 9-volt battery from the saver until the next time you need it.