Testing If Display Approx. 140.0 °C

-- Disconnect the Engine Coolant Temperature (ECT) Sensor -G62 or G83- electrical harness connector.

-- Turn the ignition switch ON.

If Indication Jumps To Approx. -40.0 °C: 

-- Switch ignition OFF.

-- Replace the Engine Coolant Temperature (ECT) Sensor -G62 or G83-.

If Indication Remains At Approx. 140.0 °C: 

Checking Wiring 

-- Remove the Motronic Engine Control Module (ECM) -J623-.

-- Disconnect the ECT harness connector at the sensor.

-- Using a multimeter, check the signal circuit of the Engine Coolant Temperature (ECT) Sensor -G62 or G83- electrical harness connector terminal 1 to engine ground. Refer to Appropriate System Diagrams for pin locations.

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 No Malfunction Is Detected In The Wiring: 

-- Replace the Motronic Engine Control Module (ECM) -J623-.

Final Procedures 

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .