Limp mode, error M55

I attached the possible causes for this and they are as simple as oil level to a control module. Clearly we will need to check these things and if they are all ok then we need to hook up a scan tool and monitor the transmission sensors when this happens.

Unfortunately this is not as simple as changing a sensor. It could be a sensor but we would just be guessing at which one. If I were going to guess and the fluid is ok, I suspect the regulator solenoid is the issue but again we will know that if we look at the sensors when it acts up.

If you don't have a scan tool that can look at transmission data then we will need to have it checked out.