Technical DPF regeneration - light?

[MKoers]

I got an 1.9 Sport from 2007.
According to the registration it has a DPF.

I was wondering when the regeneration is done.
I drive 45Km trips twice a day.
Most of the time 80Km/h on cruise control. In 6th gear ofcourse.

Sometimes (very 600Km's) the fuel consumption doubles.
Cruising a 20km/liter suddenly becomes 10km/liter.
The engine does not feel different. Not rev changes.
No lights light up.

When I stop the engine and restart it the fuel consumption is back to 20km/liter.
Even if I drive for 30 minutes straight it does not go back to the high consumption.

Is there a way to see that the car is regenerating it's DPF?
I read about a warning light.
What light do they mean, instruction manual isn't clear about this.
Does the light even turn on whens it's done.
And how long does it take?

Also I read the DPF must become at least 600 celcius to burn of the particles.
If more fuel is added it won't burn hotter as the mixture is richer (rev stays the same)
So the engine must be running leaner to create heat. So not consuming extra fuel but saving it.
At least that my theory...

Does anyone know what's the deal with al this.
And how to check if I even have a DPF., what does it look like? (a big catalyser?)

 

[Les38]

I have a 1.6 mj and the dpf is fitted next to the turbocharger on the 1.9 I believe its under the car see pic.How it actually works is a bit of a mystery but I think extra fuel for the burnoff process is injected on the exhaust stroke so would not effect performance,but as you said fuel economy would be compromised for a short time.As for the warning light Ive had issues with this as my handbook clearly shows it looking like an exhaust and is situated on the bottom left of the rev/counter,but this not the case on my car.What actualy happens is the generic warning triangle illuminates and the message "enviromental filter clogged see handbook"is shown on the digital display.Ive never had it come on whilst driving only at startup and is easily sorted by a quick 20 minute drive,a bit inconvenient at times but no big deal.In the main the dpf burnoff is automatci,under these circumstances no light is shown.Hope this helps.