Engine Coolant Temperature (ECT) Sensor, Checking

Engine Coolant Temperature (ECT) Sensor, Checking

- Connect VAG1551 or VAG1552 Scan Tool (ST) and press buttons -0- and -1 - to insert "Engine Electronics" address word 01 (engine running at idle). Refer "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1551 or VAG1552 Scan Tool" Testing and Inspection

Indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.

Indicated on display


Read Measuring Value Block
Input display group number XXX


- Press buttons -0-, -0- and -3- to input display group number 3 (003), and press -Q- button to confirm input.

Indicated on display


Read Measuring Value Block 3 ->
1 2 3 4


- Check specified values for basic functions at engine idle speed (display field 3):







- Press -> button to advance program sequence.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.


NOTE:
- The ECT sensor -G62- is a temperature- dependant resistor. If moisture should get into the connector (creating parallel resistance and causing an error in the sensor signal) the error can put the signal outside the range that is recognized by the ECM.
- If an ECT sensor malfunction is stored, the ECM calculates a replacement ECT value.


- Disconnect ECT sensor harness connector.







- Connect multimeter US1119 (Fluke 83 or equivalent) and measure resistance across sensor terminals 1 and 2, using adapter cables from VAG1594 connector test kit.







Specified resistance value (vs. temperature)

If resistance is outside specified range:
- Replace ECT sensor.
- Check readiness code. If DTC memory has been erased, generate new readiness code.
Refer to "Monitors, Trips and/or Drive Cycle (Readiness Code)/Checking, Readiness Code" Testing and Inspection
Refer to "Monitors, Trips and/or Drive Cycle (Readiness Code)/Generating, Readiness Code" Testing and Inspection

If resistance is OK:
- Connect VAG1598/19 test box to ECM harness connector. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/VAG1598/19 Test Box, Connecting" Testing and Inspection
- Disconnect ECT sensor harness connector.







- Check wiring for open circuit or short circuit to B+ or Ground between 2-pin harness connector and ECM.

2-pin ECT sensor connector terminal VAG1598/19 test box socket (ECM terminal)
1 A23
2 A19







If no wiring or sensor malfunctions are found:
- Replace ECM and generate new readiness code. Refer to "Monitors, Trips and/or Drive Cycle (Readiness Code)/Generating, Readiness Code" Testing and Inspection