Is it a serious problem if the amber "ESP" warning light comes on and stays on? I do not feel any difference in my car's performance, fuel economy, comfort or braking.
ESP, or electronic stability program, is a software-managed chassis control system.
Although different car manufacturers use terminologies such as dynamic stability control, active skid control and vehicle stability control, they all function in very much the same manner. The objective is to reduce and often totally eliminate skidding.
In conditions when the vehicle's stability limit is exceeded, whether due to human error, a sudden change in the road surface or during a sudden evasive manoeuvre, ESP will automatically intervene.
The system uses the car's anti-lock braking system to monitor individual wheel speed and, more importantly, to apply a measured amount of braking to just one wheel in order to counter the onset of oversteer or understeer.
If your vehicle's ESP warning light stays on, it means that an important electronic driving aid no longer functions.
Have it fixed immediately.