Audible DPF regeneration or something else?

When cruising on the highway, and after reaching operating temp, from time to time I hear a rapid ticking sound coming from the engine bay. The first time I heard this was when the car had only 20-30 miles on it. My first thought was that something was wrong with my brand new car, but every 500-1000 miles, I hear the sound. It lasts about 5 seconds and may come on again once or twice more within a minute or two. It sounds a lot like injectors being fired on a test bench. Is there any chance this is the sound of injectors being fired on the exhaust stroke?

Uh oh... The fact no one has responded indicates that what I'm hearing is NOT normal. Hmm.. hehe

I usually have the radio on or the windows/sunroof open, i try and listen thou.

I've never heard a ticking sound associated w/ regens, but then again I'm half-deaf. Others have opined on occasional repeated opening and closing of a relay. Any chance that's what you're hearing?

I'm not sure this is that. Other thoughts of mine are that it's the exhaust throttling valve doing some fast cycling or the intake flap valves switching rapidly. The reason I believe it may be the injectors firing on the exhaust stroke is that at 28,000 psi with no compression against the injector needle, it may be audible...

I've never noticed any clicking noises during regens, even at idle, which is when it would be easiest to hear that rapid clicking. Also, I would think that when driving it would either be happening too quickly for us to hear or road/tire/wind/other engine noise would drown it out.

Next time you hear it happening, pull over/stop as quickly and safely as possible. Verify that a regen is happening. I'm sure regens happen while cruising, but I've only ever heard/felt/smelled one at a stop.

Right, it's difficult to determine if a regen is occurring during highway driving. I'll try as you suggested, MayorDJQ, and pull over when I hear the rapid ticking in order to determine if a regen is occurring. It's quite an unusual sound that I haven't read anyone else reporting.