FC 2783 (Friction power of torque converter lockup clutch is too high) or FC 0741 (Actuation of torque converter lockup clutch not possible) stored in transmission control unit. One possible additional customer complaint could be "poor acceleration" e.g. due to engine intervention. This can affect all NAT2FE+ (7G-TRONIC PLUS) vehicles with engines OM651, OM642LS and M278 in the production period from 04/2011 to 02/2012 and with more than 10,000 km. The two fault codes can also occur in combination with rpm sensor faults (see also GI27.50-P-035556). The rpm sensor fault is not connected with this complaint.