I have been trying to penetrate the fog surrounding the replacement of the daytime running lights on my 2014 Octavia Mk III 2.0 TDI Elegant Estate to LED's.

On the face of it, changing to LED is a no brainer, saving fuel and preserving battery charge. However this may not be the case.

The factory fitted multi functional bulb provides side, daylight and dipped beam via 2 elements, but I cannot find any info on the wattage of the elements. Therefore it is impossible to determine what, if any savings can be achieved using LED's or if  they could deliver better visibility at night time.

Plus, the LED's on offer seem to be wedge fitting and one article I read says they should be H15.

Add in terms like Canbus??? and coding and my confusion is complete.

Can anyone clarify power requirements and also a functional LED replacement bulb spec?
 

A H15 is a dual filament bulb with a 55W and 15W filament which I believe is used for DRL and high/main beam in the Octavia.

 

The issue you're going to have is finding a LED equivalent that'll have the same performance when used as high beam, especially given the reflector optics. This is why there aren't that many H15 LED drop in bulb available. Assuming you normally run with DRL's on, you might be able to save 20W which is unlikely to cause the battery any issues or save any significant amount of fuel.

 

CAN-bus is a communication protocol commonly used between different control modules in modern cars. Most modern cars also have bulb monitoring circuitry so many bulbs are marketed as 'CAN-bus friendly' despite the fact they don't actually have anything to do with CAN-bus. In real terms, they normally just have an inbuilt resistor to try and fool the bulb monitoring circuitry and therefore avoid the bulb out warning. These resistors can mean the LED drop in will consume the same amount of power as a halogen bulb!

 

If a LED is not 'CAN-bus friendly' or causes bulb out warnings, it's possible to reprogram some cars to expect an LED rather than halogen to stop the bulb out warning.

 

Personally as it's a H15 I'd just leave it as a halogen...

On 16/09/2018 at 09:02, langers2k said:

A H15 is a dual filament bulb with a 55W and 15W filament which I believe is used for DRL and high/main beam in the Octavia.

 

The issue you're going to have is finding a LED equivalent that'll have the same performance when used as high beam, especially given the reflector optics. This is why there aren't that many H15 LED drop in bulb available. Assuming you normally run with DRL's on, you might be able to save 20W which is unlikely to cause the battery any issues or save any significant amount of fuel.

 

CAN-bus is a communication protocol commonly used between different control modules in modern cars. Most modern cars also have bulb monitoring circuitry so many bulbs are marketed as 'CAN-bus friendly' despite the fact they don't actually have anything to do with CAN-bus. In real terms, they normally just have an inbuilt resistor to try and fool the bulb monitoring circuitry and therefore avoid the bulb out warning. These resistors can mean the LED drop in will consume the same amount of power as a halogen bulb!

 

If a LED is not 'CAN-bus friendly' or causes bulb out warnings, it's possible to reprogram some cars to expect an LED rather than halogen to stop the bulb out warning.

 

Personally as it's a H15 I'd just leave it as a halogen...

Enlightenment!

Thank you Langers2K, much appreciated.