Repair manual

SULEV 2.0L TFSI Engine
44
Temperature Sensor Diagnostics
The temperature sensor is diagnosed in Engine Control
Module J623 only. To prevent tampering, no tests can be
performed using the VAS Scan Tool.
Furthermore, the temperature signal is not transmitted
as a voltage value, but as a LIN message. Before the ECM
can diagnose the temperature sensor, several enabling
conditions must be met. The values are then checked in
multiple measurement windows.
Enabling Conditions of the Diagnostics
– Engine temperature greater than 207.5°F (97.5°C) (so
thermostat is open)
– There is a 360-second time delay after the engine
temperature exceeds 207.7°F (97.5°C) to ensure
maximum flow through the radiator
Measurement Window is Active if:
– Engine has been idling for longer than 25 seconds
– Engine is then accelerated to part throttle or wide-
open throttle within eight seconds — intake camshaft
adjustment
– Measurement window is then active for 10 seconds in
order to measure the temperature curves (gradients)
Three Measurement Windows are Required to Decide
Whether the System is Operating Properly
Additional conditions for diagnosis:
– Diagnostics are disabled for 45 seconds at radiator fan
ON/OFF or OFF/ON
– Ambient temperature greater than 48°F (9°C)
The temperature sensor cannot be tested by reading
out a measured value. If the ECM detects a fault, the
following fault memory entries are possible:
– P2568 implausible signal
– P2569 short circuit to ground
– P2570 short circuit to battery/open circuit
– U102E LIN message incorrect (implausible signal)
– U102F timeout (no communication)
– U1030 LIN bus inactive
Note
The diagnostic strategy described in this
SSP will be replaced by a new strategy in
the course of ongoing development from
model year 2011 onward.