Why is the Check Engine indicator in Chery Bonus for no apparent reason?

The failure of the Check Engine indicator without any external malfunction of the engine normally indicates a lambda probe (oxygen sensor) failure. The sensor is sometimes malfunctioning but malfunctioning at negative temperatures-in which case the indicator is extinguishnot after the engine warm-up. If the indicator is triggered and off without a system or is permanently lit, non-quality or defective spark plugs may be the cause.