DTC 00799: Engine Coolant Temperature Sensor Circuit
WARNING: This page is about a different car, the 2003 Volkswagen EuroVan and 2002 Volkswagen EuroVan. However, it is still accessible from the selected car via links, so may be relevant.
Check engine coolant temperature sensor by reading measuring value block. See READING MEASURING VALUE BLOCK under SYSTEM TESTS. If DTCs for outside air temperature sensor, sunlight photo sensor and front vent temperature sensor also exist, check wiring and connectors from terminal No. 17 (White/Red wire) of CCM 28-pin harness connector "A" to internal splice located in CCM wiring harness. If wiring and connectors are okay, replace engine coolant temperature sensor.