A friend has a 520d sport auto lci just lost power all of a sudden on the road.

it wont rev over 1500rpm, and we drove on to a by road and would only just about crawl up a slight incline . it will start but cuts out after 5 seconds then.

while crawling up the hill it felt like the transmission was a bit rough, car was at 1000 rpm and was struggling in 1st gear, it was finding 2nd no problem when in manual mode, so I doubt it is a gearbox issue, could it be torque converter??

if it is the torque converter I presume it should still rev up, but it wont.

there is no lights coming on in the dash either, would they come on if it was an egr valve or the dpf?? as when it wont idle I was thinking it something might be blocked?

if anyone could throw a bit of lght on the subject it would be greatly appriecated

thanks in advance