Testing if display approx. 140.0°C

-- Disconnect the Engine Coolant Temperature (ECT) Sensor -- electrical harness connector -1-.

-- Turn the ignition switch ON.

Fig 1: Engine Coolant Temperature (ECT) Sensor Electrical Harness Connector

Courtesy of VOLKSWAGEN UNITED STATES, INC.

If indication jumps to approx. - 40.0°C:

-- Switch ignition OFF.

-- Replace the Engine Coolant Temperature (ECT) Sensor --. Refer to the Repair Information.

If the value remains at approx. 140.0°C

Checking wiring

-- Remove the Engine Control Module (ECM) -J623- and disconnect the ECM connectors. Refer to the Repair Information.

-- Disconnect the ECT harness connector at the sensor.

-- Using a multimeter, check the signal circuit of the Engine Coolant Temperature (ECT) Sensor -- electrical harness connector terminal 1 to engine ground.

Fig 2: 2-Pin Electrical Connector & Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Specified value: OL or no continuity.

If the specified value was Not obtained:

-- Check the wiring for a short circuit to Ground.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained:

-- Replace the Engine Control Module (ECM) -J623-. Refer to the Repair Information.