Enrichment System

1. Ensure engine is at normal operating temperature (engine oil temperature 80°C (176°F) minimum) and idle and full throttle switches are operating properly.
2. Connect suitable CO tester and tachometer.
3. Start engine and run for two minutes at idle, disconnect the throttle switch connector, then increase engine speed to 4000 RPM.
4. CO content should be 0.3-1.1%.

Note:
CO content will vary depending on altitude.

5. Using tool VW 1490, connect the throttle switch harness plug terminals together. The CO value should increase by approximately 1.5% over previous value.
6. If CO content does not increase as specified, check the wiring, and check for a defective coolant temperature sensor. If these items are good, replace Digifant II control unit.