See also:

Deposit control gasoline (detergent additives)
Volvo recommends the use of detergent gasoline to control engine deposits. Detergent gasoline is effective in keeping injectors and intake valves clean. Consistent use of deposit control gasolines ...

CHECK ENGINE Malfunction indicatorlight
On-Board Diagnostics II (OBDII): As you drive, a computer called "OBDII" monitors your vehicle's engine, transmission, electrical and emission systems. The CHECK ENGINE light will light ...

Activating/deactivating
The control panel is activated by pressing MODE when the audio system is switched on. It is switched off automatically when the audio system is switched off or by a long press on MODE. ...