Malfunction Indicator Lamp: Description and Operation

A - "MIL" exhaust emissions warning lamp
- In instrument cluster (Function of lamp)
- See Fig. 2
B - "EPC" warning lamp
- In instrument cluster (Function of lamp)
- See Fig. 3

Fig. 2 MIL exhaust emissions warning lamp






Emission-specific malfunctions recognized by the engine control module are indicated by activating the exhaust emissions warning lamp.






Exhaust emissions warning lamp (CHECK)

NOTE: Exhaust emissions warning lamp may flash or be constantly lit. DTC memory is always to be checked.


Flashing of exhaust emissions warning lamp
- A malfunction has been detected which will cause the catalytic converter damage in this driving status. In such cases, the vehicle is only to be driven at reduced power (until MIL goes out or lights constantly) and malfunction is to be repaired as quickly as possible.

Constant lighting of exhaust emissions warning lamp
- A malfunction detrimental to emissions has occurred. Check engine control module or automatic transmission DTC memory.
- In the event of engine running problems or a customer complaint without lighting of the exhaust emissions warning lamp, check operation of warning lamp and then check DTC memory, as malfunctions may also have been stored which do not immediately activate the exhaust emissions warning lamp.

Fig. 3 EPC warning lamp







"EPC" is the abbreviation for Electronic Power Control, in other words electronic engine output control (electronic throttle).

When the ignition is turned on, the engine control module switches on the EPC lamp.

After the engine is started the engine control module checks all components relevant to the operation of electronic throttle system.

During the component check, the EPC lamp lights up for approx. 3 seconds. The lamp lights continuously if a malfunction is already established in the course of this check.

If malfunctions in the electronic throttle system are detected during engine operation, the engine control module activates the EPC lamp. At the same time, an entry is made in the engine control module DTC memory.