Check Engine Light
WARNING: This page is about a different car, the 1997 Mercedes-Benz SL320, 1997 Mercedes-Benz E320, 1997 Mercedes-Benz C36, and 1997 Mercedes-Benz C280. However, it is still accessible from the selected car via links, so may be relevant.
The ECM is equipped with Diagnostic Trouble Code (DTC) memory. Malfunctions are stored as constantly present or intermittent (occurred during a trip). DTC memory is erased when battery is disconnected. Malfunctions which are no longer present are erased as follows: after 3 trips CHECK ENGINE light goes out and after an additional 40 warm-up periods, DTC is automatically erased.
A warm-up period is defined as engine coolant temperature less than 95°F (35°C) at engine start with engine coolant temperature increasing to more than 176°F (80°C). A trip is defined as follows:
- Engine running for more than 20 minutes
- Engine oil temperature more than 19°F (-7°C)
- Engine speed more than 500 RPM
- All emission related logic chain functions were checked during previous trips