Yesterday my 300 wouldn't change past first gear and rev to 3 grand at 5o kms I tried using the auto shift but all the lights on the gears came on and nothing happened.
park, neutral, and reverse all work fine but won't shift gears when driving.
i hope this is an easy fix I only bought the car a year ago and love driving it.
Sticking in second gear is "limp mode" that allows you to drive it slowly to a repair shop without needing a tow truck; definitely not at highway speed. In general, when it starts out in second gear and all the shift indicator lights are on, it's usually a sensor or other electrical problem. If it bangs back down to second gear during or right after an up-shift, it's more likely to be slippage in one of the clutch packs. Either way, there will be at least one diagnostic fault code stored in the Transmission Computer. Having those codes read is the place to start. You'll need a mechanic with a scanner that can access the Electronic Automatic Transmission Controller (EATX).