What's the 00257 vw fault code?

In Volkswagen vehicles, code 000257 indicates a failure of the mass air flow sensor. It may also manifest as P0101, and the symptoms, causes, and fixes are generally the same. You may experience loss of power or an erratic idle, resulting from the possible causes -- a faulty mass air flow sensor, air leaks around the MAF sensor, a clogged system (catalytic converter, air filter, snow screen, etc), poor grounds, or bad wiring to or from the MAF sensor. The first (and simplest) thing You should check is the intake air filter. You can also go through and inspect the wiring and ground spots. If neither of these yield any solutions, it's recommended that You test and/or replace the mass air flow sensor itself.