Audi Workshop Service and Repair Manuals > A4 Cabriolet Mk2 > Power unit | 4-cylinder engine (5-valve turbo), mechanics | Engine cooling | Removing and installing parts of cooling system | Checking map-controlled engine cooling thermostatF265

Checking map-controlled engine cooling thermostatF265

Checking map-controlled engine cooling thermostat -F265-

Special tools and workshop equipment required

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

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

Test condition

l	Engine cold

Testing internal resistance of heating element

–	Unplug connector -2- at map-controlled engine cooling thermostat -F265-.

–	Connect multimeter to thermostat to measure resistance.

l	Specification: 14 … 16 Ω at a temperature of 25 °C.

If specification is not obtained:

–	Renew thermostat → Chapter.

Function test of thermostat

–	Remove map-controlled engine cooling thermostat -F265- → Chapter.

–	Check the thermostat when cold.

l	The large valve head -arrow- must seal off the connection flange all the way round.

If not:

–	Renew thermostat → Chapter.

–	Connect the contacts of the thermostat with a battery using test leads from -V.A.G 1594 C-.

–	Using pliers, carefully place the thermostat vertically into a pot of boiling water up to the flange.

Note

t	The electric heating element now additionally heats the wax in the thermostat.

t	Do not expose the thermostat to air during this test, otherwise the expansion element can become damaged.

–	Check whether the minimum travel of -a- = 7 mm is attained after 10 minutes.

If minimum travel is attained:

–	Disconnect voltage supply from battery.

If the minimum travel is not attained:

–	Renew thermostat → Chapter.

–	Interrogate and, if necessary, erase the fault memory for the engine control unit, as faults are stored when the connector is unplugged → Vehicle diagnostic, testing and information system VAS 5051.

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