Torque Shop

My car has a feature that automatically turns on its headlights when I enter a basement, multi-storey carpark or a tunnel.

But during the day, my car seems to "forget" to turn off its auto headlights when I am out of the carpark or tunnel.

Why is this so?

Auto headlights rely on photo sensors, which are basically electronic devices that can detect the amount of ambient light outside the car.

These sensors are usually located on the dashboard at the base of the windscreen or behind the rear-view mirror.

When the ambient light level is low, the sensors will trigger the electronic controller to switch the lights on and vice versa.

Sometimes, the sensors do not react quickly enough when daylight is detected, either because the windscreen is dirty - hence limiting the amount of light passing through to the sensor - or the sensors are not sensitive enough.

Solving the first problem is easy - just wash your windscreen. As for the second problem, have your car's sensors for the auto headlights checked or replaced.

SHREEJIT CHANGAROTH

A version of this article appeared in the print edition of The Straits Times on December 17, 2016, with the headline 'Torque Shop'. Print Edition | Subscribe