It is easier to diagnose your problem if you have all codes of your car. Sometimes, one code trigger other codes. This means, if you fix the root cause of the problem, all other codes will go away. In your case, you need to get the codes to help you out.
Fail-safe mode is when the computer believes the car has critical problems and limits the speed of the van to prevent more damages to the engine or transmission.
I would not start replacing anything without knowing there is a good reason behing the recommendation.