Immobilizers are part of an electronic safety system that prevents the vehicle from cranking without the presence of the original ignition key. Immobilizers are designed to sense a microchip implant in the ignition key when inserted into the lock cylinder. There are two basic scenarios for having to troubleshoot your Volkswagon Jetta's immobilizer unit: Installing a remote starter system, which would require bypassing the immobilizer; or having to replace the ignition key or ignition switch.
Contact your local VW dealer if the ignition key has recently been replaced or a new ignition switch or lock cylinder self- installed in the VW Jetta. The dealer can fabricate a key with the correct microchip for the new ignition lock cylinder. If a new ignition key is required, contacting the dealer will be costly, however it will quickly result in deactivating the immobilizer unit.
Contact local hardware stores that may be able to duplicate micro-chipped keys with pre-installed microchips. This is a cost-saving alternative to purchasing an in-chip key from the dealer. Other retailers and key fabrication dealers specializing in in-chip keys, but they will require that the vehicle's VIN, or vehicle identification number, match that of the immobilizer system used on the vehicle. Give the retailer the VIN and, in most cases, they can identify the immobilizer unit used for the vehicle.
Install an immobilizer bypass module. This is an option if you are installing a remote starter system and you do not want to go through the dealer for a micro-chipped key. There are several bypass modules to choose from, some that cost around $20.00. Make sure that your bypass module will work properly with the Jetta's immobilizer.
Obtain a vehicle wiring diagram for the VW Jetta. These are available through Auto Zone's repair guides, VW dealers, print repair manuals or available through online resources. Some immobilizer bypass units are easy to install, while others require professional installation. If possible, look for a bypass unit that has only three to five installation wires. Wiring the bypass module will include using a wire stripper and soldering iron to join wires. Many bypass modules require removing the steering column covers and connecting the ignition switch wiring to the bypass module's wiring.
Program the Jetta's ignition key with the immobilizer bypass module using the directions provided for the module you installed.
