Engine Coolant Temperature (ECT) sensor -G2- signal, checking
If the coolant temperature display in the instrument cluster shows an incorrect reading, first check whether the signal is received by the instrument cluster.
- Connect VAS 5051 tester or VAG 1551 Scan Tool (ST). See VAS 5051 TESTER OR VAG 1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .
- Read Measuring Value Block. See READ MEASURING VALUE BLOCK (FUNCTION 07) .
- Press buttons -0-, -0- and -3- to input display group number 003, and press -Q- button to confirm input.
- Remove instrument cluster. See INSTRUMENT CLUSTER, REMOVING AND INSTALLING .
- Connect VAG1598 to blue 32-pin connector using the VAG1598/25 adapter.
- Measure resistance between socket 3 and socket 5 (sensor Ground -GND-) using multimeter (Fluke 83 or equivalent)
Specified values:
- Coolant temperature 90 °C: approx. 110 Ohm
- Coolant temperature 120 °C: approx. 50 Ohm
Check wire connection to Engine Coolant Temperature (ECT) sensor -G2- if specified values are not obtained.
- Check wire connection according to wiring diagram.
See appropriate System Wiring Diagram article.
- If specified values are not obtained, Engine Coolant Temperature (ECT) sensor -G2- must be replaced.
If the VAG 1551 scan tool displays the coolant temperature, but the coolant temperature display in the instrument cluster does not, then the instrument cluster is malfunctioning and must be replaced.
If the VAG 1551 scan tool also does not display a coolant temperature, then the signal must be checked at the multipin connector of the instrument cluster.