Car goes into limp mode every so often

Question by robertmoore posted 6 months 2 weeks ago in BMW

I have a 93 740l. It runs great on the freeway. It's problem is when l get on the off ramp. Sometimes it goes into limp mode. While in this mode l put it on a diagnostic code reader at a friend's shop. The codes were 105, 155. Since it's intermittent could it be loose wiring loose plug etc. I understand that code 105 is a speed sensor. But l havery no clue about 155.