Error 17755 & 18256: Troubleshooting & Test Box 1598/31

Dear forum,

My van (T4 V6, with a Bigas system) is causing me trouble again since my last vacation trip:

It starts with a delay, then runs on gasoline in a truly unacceptable manner; it's barely able to move, but only as long as it's not running on gas. Therefore, the following standard message may not be related to this issue at the moment:

17755 - Bank 2; Camshaft position sensor (G163) / Crankshaft position sensor (G28): Incorrect assignment.
P1347 - 35-10 - - - Intermittent.

To check the sensor, the repair manual suggests using a sensor test procedure. It specifies using a VAG test box, which I don't have. How can I perform the necessary checks as an alternative?

Edit: The question regarding MWB 208 ff. has been resolved, as it is included in the RLF.

Among the other, sometimes isolated, error messages:

17559 - Bank1; Mixed adaptation area 1: Lean limit exceeded.
P1151 - 35-10 - - - Intermittent.

17978 - Engine control unit locked.
P1570 - 35-10 - - - Intermittent.

"The following undocumented message was also displayed for the first time:"

18256 - Please read the error memory of the engine control unit.
P1848 - 35-10 - - - Intermittent.

In the latter case, the ESP light was on.

Can someone offer a constructive comment?

Thank you and best regards,
Stephan.