How to Reset the ECM & PCM on a Jettaby David Clair
The Volkswagen Jetta is equipped with an onboard computer that has different modules that control various aspects of the vehicle. The ECM is the electronic control module, which tracks and controls electronic devices in the vehicle. The PCM is the powertrain control module, which monitors and controls aspects of the Jetta's powertrain system. When either module of the computer detects a potential problem, an error code is generated. This is typically accompanied by a warning light on the control panel. Both modules of the computer can be reset using an OBD II scan tool.
Plug the cord from the scan tool into the diagnostic port, located below the steering column toward the driver's door.
Turn the ignition switch to "ON."
Press the power button on the scan tool if it does not come on automatically.
Press the "scan" or "codes" button on the scan tool if the scan does not start automatically.
Press the "clear" or "reset" button on the scan tool to reset the codes for both the ECM and PCM computer modules.