Faulty ECT Sensor: Diagnostic Procedure (GROUP 24, NO. 93-04)

FAULTY ECT SENSOR: DIAGNOSTIC PROCEDURE

TECHNICAL SERVICE BULLETIN

REPLACING ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Model(s): All Volkswagon Models With ECT Sensor

Group: 24 - Multiport Fuel Injection

Bulletin No.: 93-04

Date: November 15, 1993

CONDITION

A driveability problem can lead to the replacement of the Engine Coolant Temperature (ECT) Sensor when it is unnecessary to do so.

The following observations can lead to a suspected faulty ECT Sensor:

• VAG 1551 Scan Tool indicate ECT Sensor is faulty.
• Malfunction Indicator Light is on.
• Vehicle loses power.
• Excessive visible exhaust smoke.
• Stalling and poor idle.

Suspected ECT Sensor problems can be caused by:

• Incorrect, disconnected or faulty wiring.
• Corroded terminals.
• Faulty input to Engine Control Module (ECM).

SERVICE

Follow these steps to avoid unnecessary repairs when diagnosing suspected ECT Sensor problems.

- Determine if problem is ECT Sensor related.

- Check for correct connections at the ECT Sensor.

- Check ECT Sensor Wiring for damage.

- Check that Ground Connections are clean and make good contact.

- Check ECT Sensor Terminals (tin plated) and clean with VW Contact Cleaner, Part No. G 000 700 04, or equivalent.

- Check that Terminals are properly installed in Wiring Connectors. Use the appropriate Wiring Diagram.

- Use VAG 1598 and Digital Multimeter Fluke 83 (US 1119) to check resistance of ECT Sensor Circuit when engine is cold and again when engine is hot.

- Road test Vehicle to check performance.

- Check DTC Memory.

- Replace ECT Sensor if necessary.

- Road Test Vehicle.

- If no improvement, replace ECM.

- Road Test Vehicle.

Use the following Part Identifier Numbers:

CIS .............. 2519

Digifant I ....... 2462

Digifant II ...... 2462

Motronic 2.9 ..... 2462