Audi Workshop Service and Repair Manuals

Checking thermostat for map-controlled engine cooling system Special tools and workshop equipment required

t  Hand-held multimeter -V.A.G 1526 B-

t  Auxiliary measuring set -V.A.G 1594 C-

Testing internal resistance of heating element l  Engine cold. –  Take off engine cover panel -arrows-.

–  Unplug connector -2- at map-controlled engine cooling thermostat -F265-. –  Connect multimeter to thermostat to measure resistance. l  Specification: 14 ... 16 Ω at 25°C. If specification is not obtained: –  Renew map-controlled engine cooling thermostat -F265- → Chapter.

Function test of thermostat l  Thermostat cold. –  Remove map-controlled engine cooling thermostat -F265- → Chapter. l  The large valve head -arrow- must seal off the connection flange all the way round. If not: –  Renew map-controlled engine cooling thermostat -F265-.

–  Connect the contacts of the map-controlled engine cooling thermostat -F265- to a battery using test leads from auxiliary measuring set -V.A.G 1594 C-.   WARNING Wear protective gloves. –  Using pliers, carefully place the thermostat vertically into a pot of boiling water up to the flange. The electric heating element now additionally heats the wax in the thermostat.   Note Do not expose the thermostat to air during this test, otherwise the expansion element can become damaged. l  Check whether the minimum travel of -a- = 7 mm is attained after 10 minutes, If the specification is obtained: –  Disconnect voltage supply from battery. If specification is not obtained: –  Renew map-controlled engine cooling thermostat -F265-. –  Interrogate and erase the fault memory for engine control unit, as faults are stored when the connector is unplugged → Vehicle diagnosis, testing and information system VAS 5051.