Limp Mode Check Engine Light and Flashing Wrench

[seb1899]

On a test drive to purchase a 2015 TDI Passat SEL with 83k mi I was at a stoplight on the return drive and the car gave a lurch and a metalic "thump" and the check engine light came on as well as a little flashing wrench sign came on.
The engine reved up and the car went slowly so I guess it was in "limp mode"
Made it back to the selling dealer and they will have their mechanic look at the car on Monday.
My wife and I (she was in the car as well) had decided to write them a check and buy the car as it is very clean and the right colors and has new tires (albeit the tires are probably cheap no name "China bombs") but this event happened-glad it was the dealer's car and not mine.
What do you think triggered this fault we had been on the highway 70 mph and the bac on city streets and this happened at a stop light
Is this a car that I should avoid or is this a correctable fault that I should nottt worry about. I thought a TDI with 83k mi would be a good purchase

 

[Tom in PT]

You should place your post in the B7 forum, since the B5 forum here is for the 04-05 models.

I have no idea what triggered your fault but I would run from the car you are looking at. Suggestion: do lots of reading of all the posts in the B7 forum for the things that can and will go wrong with '12'15 Passat TDIs before you buy one. And familiarize yourself completely with the warranty the accompanied the settlement of the VW Dieselgate fiasco, which might apply to a car you purchase if you still go in this direction.

 

[seb1899]

Thanks Tom I did not realize there were distinctions between the Passat years.
I am a newb as the last VW diesel I owned was a 91 Jette Eco diesel that had a turbo. It was a great car but my wife could not learn to drive a standard so I went the 300D route. I thought the miles were reatively low and there would not be problems but I guess I should be more knowledgeable before buying as I did not know there was a DEF tank in the trunk.
I guess ignorance is blissful and thet ignorance/stupidity is not a painful condition