First problem already?

Here we go

Just popped out to lunch and about 2 minutes from the office I suddenly noticed the engine sounding way louder and "harsher" than it normally does. Not all the time, only when giving it slight throttle. If I prodded the accelerator a bit whilst above 2k rpm then rather than just taking off immediately like it normally does, there was a slight hesitation and then it went but I also noticed that, once it had "gone" and was properly under some load, the engine sounded normal again.

Stopped at the shops for 5 mins and when I came back it was still doing it so I decided to take a trip to the dealer as they're only 10 mins away. Stopped the car, popped in and came back out a couple of mins later, started it up and revved and blipped it quite a bit whilst they peered under the bonnet but it sounded normal and they could find nothing wrong. Drove it back to the office and it's been absolutely fine ever since.

Baffling! Will obvously keep an eye on it to see if it happens again but what's really strange is how it started so suddenly and then stopped just as suddenly. Almost suggests a "software" rather than "hardware" problem, such as the computer had a brain fart for a while. Surely a mechanical problem wouldn't just vanish like this unless something was loose under the bonnet, which the dealer verified wasn't the case.

Don't suppose anyone else has had any such issue with the 170 diesel engine?

Well like I said, above 2k rpm if I prod the accelerator it usually just takes off straight away but when this was happening it was a bit hesitant for a second then it would suddenly pull hard and the harshness would vanish. Could be the same thing I spose but would the EGR value explain the harshness?

Well I have another dealer not very far away so if the first one takes that attitude I'll be off to the other one and simply tell them to check it manually and ignore the computer's report. Will just let them know that if they accomodate my request I'll be far more likely to put future servicing their way

Well just been out in it again for a bit, from stone cold again (thought it might be something to do with a cold engine) and it's absolutely fine again. Weird. Hopefully the problem won't return.