"Check Engine" Lamp

TEST PROCEDURE:

Function Test:
The control unit supplies the "Check Engine" lamp with ground potential as soon as an exhaust emission-related defect is detected. As a check, the lamp lights constantly after ignition is switched "ON" and goes out as soon as the engine is running (if no exhaust emission-related defect code is stored).

Simulate Defect:
Detach connector from the air mass meter and start engine. The fault lamp must then light when the defect detected by the control unit.

Possible Defect Cause
- Control unit does not output the ground signal for the "Check Engine" lamp.
- Wires or "Check Engine" lamp defective.