This bulletin applies to 2013 Volkswagen Routan and all other models equipped with a TDI engine. If you receive a complaint of low power with a TDI engine, check the mass airflow sensor reading in measuring block, group 00, field 10.
The value should reach 255 under full load. If the reading is low, check the air filter and air box for restrictions. If OK, suspect that the MAF is at fault.