Hi, Could anyone explain when the car starts a DPF regen? Is it every time it’s driven at normal operating temp when >2000rpm? Or would it monitor how clogged it is and only start if above a certain value?

DPF regen is triggered when a certain pressure is reached across the DPF as monitored by the differential pressure sensor (basically, the higher the soot and ash content, the higher the pressure). From personal experience, once the threshold pressure is reached, it can be triggered at any engine temperature but only once a certain speed is reached (not sure what speed but the threshold is definitely between 15-30mph).

You'll be able to tell that the car is undergoing a regen if the idle RPMs are stuck at 1000 and, if the car is below operating temp, you'll notice the engine temperature increasing to operating very quickly.

Ace, thanks for that. Only had my Audi a month or so and for a 2009 it's only covered 69000 miles (previous owner was only doing short journeys) so I was expecting some DPF issues but so far I've had none. Just wondered if I should force a regen or just not worry about it. I'll be using it for long journeys anyway

My pleasure.

If it ain't broke, don't fix it (had to learn that the hard way). A service regen isn't risk free as there's been occasional stories of service regens melting the DPF. If the car is not causing issues, drive happily and worry free; let the ECU worry about the active regens as it should. Long distance driving will allow for passive regen.

I fully agree with Syed that no intervention is needed under normal driving usage.

Brilliant, thanks again.