This has been troubling me. At the end of a race, no matter if I cut the track or didn't, for some reason I always have 2 minutes added on top of my completed time, which pretty much drops me to the back of the grid. Pretty sure this is a bug, since I supposedly finished 1st and 2nd on several occasions, and I still get dropped to the back. You know where there's that timer at the end? It flashes 2:00.00 on top of the summed time. Note: I've only done these races at the Nuerburgring, so it might have something to do with the track. The 'Drive-Through' penalty was open at the time,
I did have mandatory pit stops enabled, and I did do the pit stop (4.0 seconds tyre change). Even so, at the end of the race, I still get 2 minutes added to my time. Not to mention the pit window would be displayed and would warn me if I didn't take the stop.
Here's an update: I've isolated the races and found that this problem occurs with DTM 2014. That should be useful to know.
How many tires did you change? I've found some of the pitstop rulesets require all 4 to be changed while others require only 2.
I've been busy so I haven't had time to reply. I left the ruleset at default so I'm assuming that all 4 had to be changed, and that's what I did.
They fixed a bug in the last update where you would get penalties for entering the pit lane on some tracks. So maybe your problem is fixed already.
I just ran a few races after the update and haven't run into the problem since. Guess this bug is fixed for good!